Physics Module Forces & Motion

2.1 ANALYSING LINEAR MOTION

Physics Module – Forces & Motion (by nick SMSHS)

2.1 ANALYSING LINEAR MOTION

Distance and displacement

1. Types of physical quantity:

(i) Scalar quantity: ………………………………………………………………….

(ii) Vector quantity: …………………………………………………………………

2. The difference between distance and displacement:

(i) Distance: …………………………………………………………………………

(ii) Displacement: ……………………………………………………………………

3. Distance always longer than displacement.

4. Example: The following diagram shows the location of Johor Bahru and Desaru. You can travel by car using existing road via Kota Tinggi, or travel by a small plane along straight path. Calculate how far it is from Johor Bahru to Desaru if you traveled by:a. The car

b. The plane

Solution:

Kota Tinggi

60 km

41 km 53 km

DesaruJohor Bahru

has only a magnitude

has both magnitude and direction

length of the path taken

distance of an object from a point in a certain direction

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Speed and velocity

1. Speed is ..…………………………………………………………………………………

2. Velocity is: ..……………………………………………………………………………...

3. Average of speed:

4. Average of velocity:

5. Example:

An aeroplane flies from A to B, which is located 300 km east of A. Upon reaching B, the aeroplane then flies to C, which is located 400 km north. The total time of flight is 4 hours. Calculate

i. The speed of the aeroplane ii. The velocity of the aeroplane

Solution:

the distance traveled per unit time or rate of change of distance

the speed in a given direction or rate of change of displacement

total distance traveled, s (m) , v = s m s-1

time taken, t (s) t

displacement, s (m) , v = s ms-1

Time taken, t (s) t

3

20 m s-10 m s-1 40 m s-1


Acceleration and deceleration

1. Study the phenomenon below;

Observation: ………………………………………………………………………………

2. Acceleration is, ……………………………………………………………………….

Then, a =

3. Example of acceleration;

Calculate the acceleration of car;

i) from A to B

ii) From B to C

4. Deceleration happens ...…………………………………………………………………

………………………………………………………………………………………………

5. Example of deceleration;

A lorry is moving at 30 m s-1, when suddenly the driver steps on the brakes and it stop 5 seconds later. Calculate the deceleration of lorry.

Or, a v – u t

20 m s-10 m s-1 40 m s-1

A B C

t = 2 s t = 2 s

20 – 0 2= 10 m s-2

The velocity of the car increases.

the rate of change of velocity

when the velocity of an object decreases, In calculations, a

will be negative

4

. . . . . . . .

. . . . . . . .

. . . . . . . .

. . . . . . . .

8

7

6

5

4

3

2

1

0

u

v


Analysing of motion

1. Linear motion can be studied in the laboratory using a ticker timer and a ticker tape.

(i) Determination of time:

(ii) Determination of displacement as the length of ticker tape over a period of time.

x y

(iii) Determine the type of motion;

………………………………………………

...……….……………………………………

.……………………………………………..

(iv) Determination of velocity

displacement = ……………………… time = ………………………………..

Velocity, v =

(v) Determine the acceleration

Length/cm

ticks

. . . . . . .

. . . . . . .

5

Length / cm

16

12

8

4

0

A B C Time/s


Execise 2.1.1

1. Figure 2.1 shows a tape chart consisting of 5-tick strip. Describethe motion represented by AB and BC.In each case, determine the ;

(a) displacement

(b) average velocityigure 2.1

(c) acceleration

2. A car moving with constant velocity of 40 ms-1 . The driver saw and obtacle in front and he immediately stepped on the brake pedal and managed to stop the car in 8 s. The distance of the obstacle from the car when the driver spotted it was 180 m. How far is the obstacles from the car has sttoped.

Execise 2.1.2

Note : The frequency of ticker timer is 50 Hz.

1. The diagram shows a ticker tape obtained from the motion of a trolley.

A 20 cm B

Calculate the speed from A to B.

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2. The diagram shows a ticker tape obtained from the motion of a trolley.

30 cm 5 cm

Calculate thea) initial speedb) final speedc) time interval between the two speedd) accelerationof the trolley.

3. The diagram shows a ticker tape chart obtained from the motion of a trolley.

Each strip contains 5 ticks. Calculate thea) initial speedb) final speedc) time interval between the two speedd) acceleration of the trolley.

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Execise 2.1.3

1. A boat takes 30 seconds to travel 500 west. It then changes its direction and moves 500 m north in 20 seconds. Calculate thea) i) total distance

ii) displacementb) i) average speed

ii) average velocity of the boat

2. Xiao Long cycles down a slope from a rest with a uniform acceleration of 1.25 ms -2. He reaches the bottom in 14 seconds. Determine his a) final velocityb) displacement

Without stopping, he then cycles up an adjacent slope with a uniform deceleration until he comes to a rest after traveling a distance of 60 m. Determine the deceleration.

3. A car moving at 40 ms-1 decelerates uniformly to a stop after traveling a distance of 10 m. What is his deceleration.

4. A man running at 5 ms-1 decelerates uniformly to a stop after traveling a distance of 10 m. What is his deceleration?

5. A car moving at 20 ms-1 starts to slow down at 4 ms-2 when it comes to a junction. Calculate the distance travelled before it comes to a stop.

6. In an investigation, a toy car is pulled with a constant force to move on a smooth horizontal plane from rest. The velocity of the toy car after 6 s is 9 ms-1.i) What is the acceleration of the toy car?ii) Determine the displacement of the toy car in 6 s.

7. A train moving at 20 ms-1 takes 10 s to accelerate to 25 ms-1. i) Calculate its average acceleration.ii) Calculate the distance it travels while it accelerates.

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2.2 ANALYSING MOTION GRAPHS

The data of the motion of the car can be presented………………………………….

The displacement-time Graph

0m 100m 200m 300m 400m 500m displacement0s 10s 20s 30s 40s 50s time

a) displacement (m) Graph analysis:

………………………………………………………………

………………………………………………………………

time (s) ……………...………………………………………………

b) displacement (m) Graph analysis:

……..…………………………………………………………

…………………………………………………………………

time (s) ……….…………………………………………………………

c) displacement (m) Graph analysis:

…….……………………………………………………………

…………………………………………………………………

time (s)………………………………………………………………

d) Displacement (m) Graph analysis:

…………………………….……………………………

……………………………………………..……………

time (s) …………………………………………………………

…………………………………………………………

in the form of graph called a motion graphs

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The velocity-time Graph

c) v (m s-1)

t1 t2 t (s)

e) displacement (m) Graph analysis:

…………………………………………………………..

…………………………………………………………..

………………………………………………………….. time (s)

…………………………………………………………..

f) displacement (m) Graph analysis:

A B …………………………………………………………..

…………………………………………………………..

…………………………………………………………… O C time (s)

a) v/ m s-1 Graph analysis:

…………………………………………………………..

…………………………………………………………..

……………………………………………………………

t t / s

b) v/ m s-1 Graph analysis:

………………………………………..………………..

…………………………………………………………

…………………………………………………………

t t / s

Graph analysis:

………………………………………..………………..

…………………………………………………………

…………………………………………………………

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O

P Q

R

S

0 2 4 6 8 t/s


d) v (m s-1)

t (s)

e) v (m s-1)

t (s)

Examples

1. s/m

2.

O

P Q

R

v/m s-1

10

5

0 2 4 6 8 10 t/s

Calculate:- (i) acceleration,a over OP, PQ and QR(ii) Displacement

Solution :

Calculate:- (i) Velocity over OP, QR and RS(ii) Displacement

Solution :

Graph analysis:

………………………………………..………………..

…………………………………………………………

…………………………………………………………

Graph analysis:

………………………………………..………………..

…………………………………………………………

…………………………………………………………

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Excercise 2.2

1. (a) s/m (b) s/m (c) s/m

10

t/s 0 2 4 t/s

t/s

-5 -10

Diagram 2.21

Describe and interpret the motion of a body which is represented by the displacementtime graphs in Diagram 2.21

……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………

2. Describe and interpret the motion of body which is represented by the velocity-time graphs shown in Diagram 2.22. In each case, find the distance covered by the body and its displacement

(a) v/m s-1 (b) v/m s-1

10

t/s 0 2 4 t/s

-5 -10

Diagram 2.22

……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………

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2.3 UNDERSTANDING INERTIA

1. Meaning of inertia :

…………..………………………………………………………………………………….

………………………………………………………………………………………………

2. The relationship between mass and inertia : ……………………………….

……………………………………………………………..

Effects of inertia

1. Positive effect : …………………………………………………………………………

2. Negative effect : ………………………………………………………………………….

Example:

A wooden dowel is fitted in a hole through a wooden block as shown in figure above. Explain what happen when we

(a) strike the top of the dowel with a hammer,

(b) hit the end of the dowel on the floor.

Application of inertia

1. Drying off an umbrella by moving and stopping it quickly.

2. Building a floating drilling rig that has a big mass in order to be stable and safe.

3. To tight the loose hammer

We should take a precaution to ovoid the effect.

1. During a road accident, passengers are thrust forward when their car is suddenly stopped.

2. Passengers are hurled backwards when the vehicle starts to move and are hurled forward

when it stops immediately.

3. A person with a heavier/larger body will find it move difficult to stop his movement.

4. A heavier vehicle will take a long time to stop.

A wooden block move up of a wooden dowel.

A wooden block has inertia to remains at rest.

The wooden block move downward of a wooden dowel.

A wooden block has inertia to continue it motion.

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(mb + mg)

mg vg = 0

mb

vb&g Starting position before she catches the ball

vb

Receiving a massive ball

mb

vb

mg

vg

Starting position before she throws the ball

Throwing a massive ball


2.4 ANALYSING MOMENTUM

Idea of momentum

1. When an object is moving, …...…………………………………………………………

2. Momentum is defined …………………………………………………………………….

………………………………………………………………………………………………

Conservation of momentum

The principle of conservation of momentum :

………………………………………………………………………………………………………

………………………………………………………………………………………………………

i

t

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1. Elastic collision .…………………………………………………………………………..

Before collision after collision

2. Inelastic collision :………………………………………………………………………...

Before collision after collision

3. explosion : …….....…………………………………………………………………...

Before explosion after explosion

Example 1 :

Car A Car B

Car A of mass 100 kg traveling at 30 m s-1 collides with Car B of mass 90 kg traveling at 20 m s-1 in front of it. Car A and B move separately after collision. If Car A is still moving at 25 m s-1 after collision, determine the velocity of Car B after collision.

Solution :

m1

m2 m1m2

u2 v2

u1

m1 m2 m1 + m2

u2 = 0

u1

v

(m1 + m2), u = 0 v1

m2

v2

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Example 2 :

Car A of mass 100 kg traveling at 30 m s-1 collides with Car B of mass 90 kg traveling at 20 m s-1 in front of it. Car A is pulled by Car B after collision. Determine the common velocity of Car A and B after collision.

Solution :

Example 3 :

A bullet of mass 2 g is shot from a gun of mass 1 kg with a velocity of 150 m s-1 . Calculate the velocity of the recoil of the gun after firing.

Solution :

Exercise 2.4

1. An arrow of mass 150 g is shot into a wooden block of mass 450 g lying at rest on a smooth surface. At the moment of impact, the arrow is travelling horizontally at 15 ms-1. Calculate the common velocity after the impact.

2. A riffle of mass 5.0 kg fires a bullet of mass 50 g with a velocity of 80 m s-1 .Calculate the recoil velocity. Explain why the recoil velocity of a riflle is much less than the velocity of the bullet.

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Stationary object


2.5 UNDERSTANDING THE EFFECT OF A FORCE

Idea of force

1. What will happen when force act to an object?

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

Idea of balanced forces

1. An object is said to be in balance when it is:

………………………………………………………………………………………………

………………………………………………………………………………………………

2. Stationary object

……………………………… explanation :

3. An object moving with uniform velocity

explanation :

Idea of unbalanced forces

1. A body is said to be in unbalanced..……………………………………………………

2. Explanation;

1. In a stationary state

2. Moving at uniform velocity

Normal reaction, N

Magnitude R = W but R acts in an

opposite direction to the weight.

( object is in equilibrium )

weight, w = mg

Normal reaction, N

Frictional force Force, F Force , F = Friction

Resultant = F – Friction

= 0 (object is in equilibrium)

weight, w = mg Examples :

1.A car move at constant velocity.

2.A plane flying at constant velocity.

when it is moving in acceleration.

Resultant force

The ball move in acceleration

because the forces act are not

balanced. F > F’

F F’ So, the ball move in F direction

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Relationship between forces, mass and acceleration (F = ma)

Example 1 : Calculate F, when a = 3 m s-2 dan m = 1000 kg

Example 2 :

Calculate the acceleration, a of an object.

Exercise 2.5

1. A trolley of mass 30 kg is pulled along the ground by horizontal force of 50 N. The opposing frictional force is 20 N. Calculate the acceleration of the trolley.

2. A 1000 kg car is travelling at 72 km h-1 when the brakes are applied. It comes to a stop in a distance of 40 m. What is the average braking force of the car?

2.6 ANALYSING IMPULSE AND IMPULSIVE FORCE

Impulse and impulsive force

1. Impulse is ……………………………………………………………………………….

2. Impulsive force is ………………………………………………………………………

………………………………………………………………………………………………

3. Formula of impulse and impulsive force:

m = 25 kgm = 25 kgF = 200 NF = 200 N

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Example 1; v u

wall

If ; u = 10 m s-1 , v = - 10 m s-1 , m = 5 kg and t = 1 s

Impulse, Ft = and impulsive force, F =

Example 2; v u

Wall with a soft surface

If ; u = 10 m s-1 , v = - 10 m s-1 , m = 5 kg and t = 2 s

Impulse, Ft = and impulsive force, F =

4. The relationship between time of collision and impulsive force.

………………………………………………………………………………………………

Exercise 2.6

1. A force of 20 N is applied for 0.8 s when a football player throws a ball from the sideline. What is the impulse given to the ball?

2. A stuntman in a movie jumps from a tall building an falls toward the ground. A large canvas bag filled with air used to break his fall. How is the impulsive force reduced?

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Safety features in vehicles

Crash resistant door pillars

Anti-lock brake system (ABS)

Traction control bumpers

Windscreen

Air bags

Head rest

Crumple zones


2.7 BEING AWARE OF THE NEED FOR SAFETY FEATURES IN VEHICLES

Importance of safety features in vehicles

Safety features Importance

Padded dashboardIncreases the time interval of collision so the impulsive force produced during an impact is thereby reduced

Rubber bumper Absorb impact in minor accidents, thus prevents damage to the car.

Shatter-proof windscreen Prevents the windscreen from shattering

Air bagActs as a cushion for the head and body in an accident and thus prevents injuries to the driver and passengers.

Safety seat beltPrevents the passengers from being thrown out of the car. Slows down the forward movement of the passengers when the car stops abruptly.

Side bar in doorsPrevents the collapse of the front and back of the car into the passenger compartment. Also gives good protection from a side-on collision.

Crumple zone

Reinforced passenger compartment

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2.8 UNDERSTANDING GRAVITY

Acceleration due to gravity.

1. An object will fall to the surface of the earth because………………………………...

2. The force of gravity also known ………………………………………………………...

3. When an object falls under the force of gravity only, ………………………………...

4. The acceleration of objects falling freely ………………………………………………

5. The magnitude of the acceleration due to gravity depends ………………………...

Gravitational field

1. The region around the earth is ………………………………………………………….

2. The object in gravitational field …………………………………………………………

3. The gravitational field strength is defined ……………………………………………..

4. The gravitational field strength, g can be calculate as;

5. At the surface of the earth, …………….

………………………………………………………………………………..

6. This means

……………………………………………………………………………………………..

Example 1. Can you estimate the gravitational force act to your body?mass = 60 kg, g = 9.8 N kg-1, F = ?

Example 2,A satellite of mass 600 kg in orbit experiences a gravitational force of 4800 N. Calculate the gravitational field strength.

Example 3,A stone is released from rest and falls into a well. After 1.2 s, it hits the bottom of the well.(a) What is the velocity of the stone when it hits the bottom?

(b) Calculate the depth of the well.

It pulled by the force of gravity.

as earth’s gravitational force.

the object is said to be free falling

is known as acceleration due to gravity.

on the strength of the gravitational field

the gravitational field of the earth.

is on the force of gravity.

as the gravitational force acting on a 1 kg mass.

. g = F . where, F : gravitational force m m : mass of an object

g = 9.8 N kg-1 10 Nkg-1 = 10 ms-2

that an object of mass 1 kg will experience a gravitational force of 9.8 N.

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Weight

1. The weight of an object is defined ……………………………………………………..

2. For an object of mass m, the weight can be calculate as :

Example :The mass of a helicopter is 600 kg. What is the weight of the helicopter when it land on the peak of a mountain where the gravitational field is 9.78 N kg-1?

Exercise 2.8

1. Sketch the following graphs for an object that falling freely.

(a) Displacement-time graph,(b) Velocity-time graph(c) Acceleration-time graph

2. The following data was obtained from an experiment to measure the acceleration due to gravity.Mass of steel bob = 200 g, distance covered = 3.0 m, time of fall = 0.79 s.Calculate the acceleration due to gravity of steel bob.Give the explanation why your answer different with the constant of gravitational acceleration, g = 9.8 m s-2.

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2.9 IDEA OF EQUILIBRIUM FORCES

An object is in equilibrium when :

1. ………………………………………………………………………………………………

2. ………………………………………………………………………………………………

stationary object

An object moving with uniform velocity

Addition of Force

1. Addition of force is defined as ...……………………………………………………..

………………………………………………………………………………………………

………………………………………………………………………………………………

Examples : the forces are acting in one direction

F1 = 10 N

F2 = 5 N

Resultant force, F

Example : the forces are acting in opposite directions

F1 = 10 N

F2 = 5 N

Resultant force, F

a resultant force is a single force the

represents in magnitude and direction two or more forces acting on an object

F resultant = the total of forces (including the directions of the forces)

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Example : the forces are acting in different directions

F2 = 5 N

500

F1 = 10 N

Parallelogram method:

1. Draw to scale.

2. Draw the line parallel with F1 to the edge of F2, and the line parallel with F2 to the

edge of F1

3. Connect the diagonal of the parallelogram starting from the initial point.

4. Measure the length of the diagonal from the initial point as the value of the

resultant force.

F2

F1

Triangle method

1. Draw to scale.

2. Displace one of the forces to the edge of another force.

3. Complete the triangle and measure the resultant force from the initial

point.

Example 1: During Sport Day two teams in tug of war competition pull with forces

of 6000 N and 5300 N respectively. What is the value of the resultant

force? Are the two team in equilibrium?

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Example 2: A boat in a river is pulled horizontally by two workmen. Workmen A

pulls with a force of 200 N while workmen while workmen B pulls with

a force of 300 N. The ropes used make an angle 250 with each other.

Draw a parallelogram and label the resultant force using scale of 1 cm :

50 N. Determine the magnitude of resultant force.

Resolution of a force

1. Resolution of a force is …………………………………………………………………

Refer to trigonometric formula:

Example : The figure below shows Ali mopping the floor with a force 50 N at an angle of 600 to the floor.

F = 50 N

reverse process of finding the resultant force

Fy F is the resultant force of Fx and Fy Therefore, F can be resolved

into Fx and Fy F

Vertical Component

Fx horizontal component

Cos =

F x

F , therefore Fx = F cos

Sin =

F y

F , therefore Fy = F sin

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Example of resolution and combination of forces

Problem solving

1. When a system is in equilibrium, ……………………………………………………….

2. If all forces acting at one point are resolved into horizontal and vertical

components, ……………………………………………………………………………

3. Example 1; Show on a figure;

a) the direction of tension force, T of stringb) the resultant force act to lampc) calculate the magnitude of tension force, T

a)

mlamp = 1.5 kg

Wlamp = 14.7 N

Exercise 2.9

1. Two force with magnitude 18 N and 6 N act along a straight line. With the aid of diagrams, determine the maximun possible value and the minimum possible value of the resultant force.

2. A football is kicked simultaneously by two players with force 220 N and 200 N respectively, as shown in Figure 2.9. Calculate the magnitude of the resultant force.

220 N

900

200 N

F = ?

200 N

400

T b) T’ T700 700

the resultant force is equal to zero.

the sum of each component is equal to zero.

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2.10 UNDERSTANDING WORK, ENERGY AND EFFICIENCY

Work

1. Work is done, ……………………………………………………………………………..

………………………………………………………………………………………………

2. WORK is the product.…………………………………………………………………….

3. The formula of work;

Example 1;

80 N

600

s = 5 m

Example 1;

Example 3;

F = 600 N

s = 0.8 m

When a force that acts on an object moves the object through a

distance in the direction of the force.

of a force and the distance traveled in the direction of the force.

W = F x s

T T

F = 30 N h = 1.5 m

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s

Force, F


Energy

1. Energy is .................................................................................................................

2. Energy cannot be ....................................................................................................

3. Exist in various forms such as …………………...……………………………………

………………………………………………………………………………………………

Work done and the change in kinetic energy

1. Kinetic energy is …………………………………………………………………………

2. Refer to the figure above,

Example 1;A small car of mass 100 kg is moving along a flat road. The resultant force on the car is 200 N.a) What is its kinetic energy of the car after moving through 10 m?b) What is its velocity after moving through 10 m?

Work done and gravitational potential energy

h = 1.5 m

1. Gravitational potential energy is………………………………………………………...

………………………………………………………………………………………………

2. Refer to the figure above;

Example;

If m = 10 kg, gravitational potential energy = ………………………………………….

Through, v2 = u2 +2as u = 0

and, as = ½ v2

It is the potential to do work.

created nor be destroyed.

potential energy, kinetic energy, electrical

energy, sound energy, nuclear energy and chemical energy.

energy of an object due to its motion.

Work = Fs = mas = m ( ½ v2)

The formulae of Kinetic energy, Ek = ½ mv2

energy of an object due to its position.

(possessed by an object due to its position in a gravitational field)

W = Fs = mg h where, F = mgSo, Gravitational energy, Ep = mgh

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Principle of conservation of energy

To show the principle of conservation of energy.

1. Energy cannot be ………………………………………………………………………

2. Example : a thrown ball upwards will achieve a maximum height before changing its direction and falls

Example:A coconut falls from a tree from a height of 20 m. What is the velocity of coconut just before hitting the earth?

Power

1. Power is …………………………………………………………………………………

2. A weightlifter lifts 180 kg of weights from the floor to a height of 2 m above his head in a time of 0.8 s. What is the power generated by the weightlifter during this time? g = 9.8 ms-2)

created or destroyed but can be changed from one form to another form.

Maximum Potential energy

Kinetic energy decrease potential energy decreaseand potential energy and kinetic energyIncrease increase

Maximum kinetic energy

the rate of doing work.

Therefore, power, P =

workdonetimetaken , so, P =

Wt

Where, P : power in watt/WW : work in joule/J t : time to do work in seconds/s

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Efficiency

1. Defined……..…………………………………………………………………………….

2. Formulae of efficiency :

3. Analogy of efficiency;

Energy transformation

Example; An electric motor in a toy crane can lift a 0.12 kg weight through a height of 0.4 m in 5 s. During this time, the batteries supply 0.8 J of energy to the motor. Calculate(a) The useful of output of the motor.

(b) The efficiency of the motor

Exercise 2.10

1. What is the work done by a man when he pushes a box with a force of 90 N through a distance of 10 m? State the amount of energy transferred from the man to the force.

2. A sales assistant at a shop transfers 50 tins of milk powder from the floor to the top shelf. Each tin has a mass of 3.0 kg and the height of thee top shelf is 1.5 m.

(a) Calculate the total work done by the sales assistant.

(b) What is his power if he completes this work in 250 s?

Device/ mechineDevice/ mechine

as the percentage of the energy input that is transformed into useful energy.

Efficiency=Useful energy outputEnergy input

×100 %

unwanted energy

Energy input, Einput Useful energy, Eoutput

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2.11 APPRECIATING THE IMPORTANCE OF MAXIMISING THE EFFICIENCY OF DEVICES

1. During the process of transformation the input energy to the useful output energy,

……………………………………………………………………………………..

2. .……………………………………………………………………………………………..

3. ………………………………………………………………………………………………

Example of wasting the energy;

………..…………………

Input enegy from the petrol output energy

4. The world we are living in face acute shortage of energy.

5. It is very important that a device makes

…………………………………………………………………

Ways of increasing the efficiency of devices

1. Heat engines ……………………..………………………………………………………

………………………………………………………………………………………………

2. Electrical devices. ...……………………………………………………………………...

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

Operation of electrical devices

1. The electrical devices increase the efficiency………………………………….……

2. Proper management ….....………………………………………………………………

3. …………..………………………………………………………………………………

some of energy transformed into unwanted forms of energy.

The efficiency of energy converters is always less than 100%.

The unwanted energy produced in the device goes to waste.

Kinetic energy

Energy loss due to Energy loss Energy loss Energy loss due to friction at friction in as heat as sound other parts in the moving parts engine

the best possible use of the input energy.

Engine must be designed with the capability to produce greater amount

of mechanical work.

Light Fittings

- replace filament light bulb with fluorescent lamps which have higher efficiency.

- use a lamp with a reflector so that the illumination can be directed to specific areas

of the user.

Air-conditioners.

- choose a model with a high efficiency.

- accommodate the power of air-conditioner and the size of the room

- Ensure that the room totally close so that the temperature in the room can be

maintained.

when they are in good operating

condition.will increase the life span of device.

Example : the filter in an air-conditioner and fins of the cooling coil of a refrigerator

must be periodically cleaned.

31


2.12 UNDERSTANDING ELASTICITY

1. Elasticity is ……………………………………………………………………………...

………………………………………………………………………………………………

2. Forces between atoms …………………………………………………………………..

………………………………………………………………………………………………

3. Forces between atoms in equilibrium condition

Explanation :

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

4. Forces between atoms in compression

Explanation ;

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

5. Forces between atoms in tension

force of attraction

stretching force stretching force

Explanation ;

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

Force of repulsion

Force of attraction

Force of repulsion

compressive forcecompressive force

Force of repulsion Force of repulsion

the property of an object that enables it to return its original shape and

dimensions after an applied external force is removed.

The property of elasticity is caused by the existence of forces of

repulsion and attraction between molecules in the solid material.

1. The atoms are separated by a distance called the equilibrium distance and

vibrate at it position.

2. Force of repulsion = Force of attraction

1. Force of repulsion takes effect.

2. When the compressive force is removed, force of repulsion between the atoms pushes

the atom back to their equilibrium positions.

1. Force of attraction takes effect.

2. When the compressive force is removed, force of repulsion between the

atoms pushes the atom back to their equilibrium positions.

32


Hooke’s Law

1. Hooke’s Law states ………………………………………………………………………

………………………………………………………………………………………………

2. Elastic limit of a spring is defined……………………………………………………….

………………………………………………………………………………………………

3. The spring is said to have a permanent extension,...…………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

4. The elastic limit is not exceeded,…………………………………………….…………

………………………………………………………………………………………………

5. Graf F against xGraf F against x

F/ N

6. Spring Constant, k

F/N

0.8

0 8 x/cm

Example 1; A spring has an original length of 15 cm. With a load of mass 200 g attached, the length of the spring is extend to 20 cm. a. Calculate the spring constant. b. What is the length of the spring when the load is in increased by 150 g?

[assume that g = 10 N kg-1]

x (cm)0

EQ P

R

that the extension of a spring is directly proportional to the applied

force provided that the elastic limit is not exceeded.

as the maximum force that can be applied to

spring such that the spring will return to its original length when the force released.

when the length of the

spring longer than the original length even though the force acts was released and the

elastic limit is exceeded.

When the spring obey Hooke’s Law.

The mathematical expression for Hooke’s Law is : F µ x

F = kx, k = Force constant of the spring

Force constant, k = F with unit N m-1, N cm-1 or N mm-1

x

F = kx Spring obeying Hooke’s Law Spring not obeying Hooke’s law

(exceeded the elastic limit)

Force constant, k = F with unit N m-1, N cm-1 or N mm-1

x

33

F (N)

x (cm)

P

Q

8

7

6

5

4

3

2

1

0

0.1 0.2 0.3 0.4 0.5

Graph F against x of spring P and spring Q

x / cm

F/N

F x

15 cm

5 kg

8 cm


Example 2;

Elastic potential energy

1. Elastic potential energy ………………………………………………………………..

spring with the original length

F compression

spring compressed

spring extended

Other situation where the spring extended and compressed

Relationship between work and elastic potential energy

Graph F against x

Example ;

The graph shows the relationship between the stretching force, F and the spring extension, x. (a) Calculate the spring constant of P and Q.(b) Using the graph, determine the stretching force acts to spring P and spring Q, when their extension are 0.5 cm

the energy stored in a spring when it is extended or compressed

Area under the graph = work done = ½ FxSo, Elastic potential energy = ½ Fx

34


Factors that effect elasticity

Hands-on activity 2.13 on page 42 the practical book to investigate the factors that affect elasticity.

Type of material different same same same

Diameter of spring wire same different same same

Diameter of spring same same different same

Length of spring same Same same different

Summarise the four factors that affect elasticity

Factor Change in factor Effect on elasticity

LengthShorter spring Less elastic

Longer spring More elastic

Diameter of springSmaller diameter Less elastic

Larger diameter More elastic

Diameter of spring wireSmaller diameter More elastic

Larger diameter Less elastic

Type of material the elasticity changes with the type of materials

Exercise 2.12

1. A 6 N force on a spring produces an extension of 2 cm. What is the extension when the force is increased to 18 N? State any assumption you made in calculating your answer.

2. If a 20 N force extends a spring from 5 cm to 9 cm,(a) what is the force constant of the spring?

(b) Calculate the elastic potential energy stored in the spring.

35


1. A tick on a ticker tape means …….

A. the distance between two dotsB. the time taken to make two consequence dots.C. the speed of the motion of the ticker tape.D. The frequency of the vibration.

2. Diagram shows a ticker tape is pulled by a trolley.

The trolley acceleration is….. A decreased B constant C increased

3. An oil drips at a constant rate from a moving car. The diagram shows the pattern of the drips on the road.Minyak menitis pada kadar seragam dari kereta yang sedang bergerak. Gambar rajah menunjukkan corak titisan di atas jalan raya.

Which statement describes the motion of the car?Manakah pernyataan yang menerangkan gerakan kereta tersebut?

A It accelerated and then moved at a steady speed.Ia memecut dan kemudiannya bergerak dengan laju seragam.

B It accelerated and then decelerated.Ia memecut dan kemudiannya menyahpecut.

C It moved at a steady speed and then decelerated.Ia bergerak dengan laju seragam dan kemudiannya menyahpecut.

D It moved at a steady speed and then accelerated.Ia bergerak dengan laju seragam dan kemudiannya memecut.

Direction of movement

1.0 cm 1.5 cm 2.0 cm 2.5 cm

arah gerakan

36


4. A boy walks 8 m due east from a point R and then 6 m due north. What is the total distance travelled?

A 2 mB 10 mC 14 mD 28 mE 48 m

5. Diagram shows a track for 200m event. An athlete has finished the race in 25 s.Rajah menunjukkan trek bagi acara larian 200 m.Seorang atlit telah menamatkan larian dalam acara tersebut dalam masa 25 s.

What is the velocity of the athelete ? Berapakah halaju atlit itu ?

A.

35025 B.

20025 C.

15025 D.

25150 E.

25200

6. If acceleration is zero, the velocity is

A. zero C. increases constantlyB. constant D. decreases constantly

7. Diagram shows the path taken by a cyclist along a rectangular track.

6 m

8 m

A 6 m C 10 m E 28 mB 8 m D 14 m

37

2

Lenght, l/cm


8. The table gives the information about the motion of four cars. Which car moved with the largest average speed?

Distance travelled (m) Time taken (s)A 899 23B 792 19C 851 21D 811 20

9. A lorry starts from rest with a constant acceleration of 3 ms−2

. What is its velocity after 6 seconds?

A 0.5 ms−2

B 2.0 ms−2

C 18.0 ms−2

D 36.0 ms−2

E 40.0 ms−2

10. Figure shows a section of a ticker tape which was pulled by a trolley through a ticker timer .

Direction of motion

If the ticker timer is operated by a power supply with a frequency of 50 Hz, what is the acceleration of the trolley ?

A 5 ms-2 B 8 ms-2

C 10 ms-2 D 20 ms-2

11. The diagram shows a tape charts. Every strip has 5 ticks.

If the frequency used is 50 Hz , calculate the acceleration A 50.0 cms-2 B 60.0 cms-2 C 80.0 cms-2

D 90.0 cms-2 E 100.0 cms-2

. . . . . . . . . . . .

0.4 cm 2.4 cm

6

38


12. Figure shows a trolley placed on a friction-compensated runway. The trolley will ….

A. move with an increasing velocity.B. move with decreasing velocity.C. move with a constant velocity.D. remain stationary.

13. The cylinder oil tank of En. Ali’s car is leaking. Lubricant spot are seen along the road from A to B as shown below.

It can be concluded that En Ali’s car is moving with …

A constant acceleration B constant decelerationC zero acceleration D acceleration that is decreasing constantly.

14. Diagram below is a graph which shows the displacement-time graph of four objects.

s / m

AB

C

D

0 t / s

Which object is at rest?

A. Object A B. Object B C. Object C D. Object D

A B

En. Ali’s car

10 m 15 m 20 m

39


15. Which displacement-time graph represent the motion of an object moving at constant velocity ? Graf sesaran –masa yang manakah berikut mewakili pergerakan suatu objek dengan halaju tetap ?

16. Diagram shows the velocity – time graph of an object. v / ms-1

0 t / s

Which of the following statements is correct.

A. The displacement of the object is zero.B. The gradient of the graph represents the displacement of the object.C. The area under the graph represents the displacement of an object.

s/m

t/s

s/m

t/s

A B

s/m

t/sC

s/m

t/s

D

40


17. Which graph shows an increasing acceleration?

A B

C D

18. Diagram shows the acceleration-time graph of two cars traveling on a straight road.

a / m s-2

Car A Car B

X

Y

t / s

Which of the following statements is correct?.

A. Car A changed its speed at point X.B. The two cars move at same speed all the time.C. Car B has a larger acceleration than Car B.

41

Displacement (m)

10

0 2 4 6 8Time (s)


19. A van accelerates from rest position. The acceleration is decreased while going up a hill. Which of the following graphs represent the change of velocity of the van, v varies with time ,t ? Sebuah van memecut dari keadaan pegun. Pecutannya semakin berkurang apabila menaiki bukit. Graf manakah menunjukkan perubahan halaju, v dengan masa, t van tersebut ?

20. Diagram shows a displacement – time graph for the motion of an object.

The momentum of the object is zero from

A 0 s to 2 sB 2 s to 4 sC 2 s to 6 sD 6 s to 8 sE 0 s to 8 s

21. Figure shows the velocity-time graphs of Adnan, Hamid and Lim respectively travelling along a straight road.

42

1 2 3 4

6

4

2

v/ms-1

t/s

6

v/ms-1

t/s

v/ms-1

20

15

7 15 25 t/s


If all the three of them started their journey from the same place at the same time, arrange their name in accordance to increasing order of their displacements from the starting point.

A. Adnan, Hamid, Lim C. Adnan, Lim, HamidB. Hamid,Lim, Adnan D. Lim, Adnan, Hamid

22. Figure shows the velocity-time graph of a moving object. From the following statements, which one is true regarding the acceleration of motion?

A Acceleration occurs at the first seven seconds.B The acceleration and deceleration respectively are non uniform after the

first seven seconds.C The value of the acceleration is bigger than the value of deceleration.D The acceleration is zero for the first seven seconds.

23. Which of the following graphs show motion at a constant velocity?

1 2 3 4

6

4

v/ms-1

t/s

1 2 3 4

Adnan Hamid

Lim

43

A

time

displacement

time

acceleration

time

velocity

time

acceleration

B

C

D

16

12

0 10 20 25 t/s

v/ms-1


24. The graph shows the motion of a car in a straight line.Graf menunjukkan halaju – masa bagi satu gerakan.

What is the time taken by the car to travel at a distance of 260 m?Berapakah masa yang diambil oleh kereta itu untuk bergerak sejauh 260 m?

A 5 seconds C 15 seconds 5 saat 15 saat B 10 seconds D 20 seconds 10 saat 20 saat

44


25. Diagram shows a graph of velocity versus time for a car driver. Which of the following statements expresses the conclusion made based on the graph?.

A. The initial acceleration of the driver was 4 m s-2

B. The deceleration of the car was 4 m s-2

C. The total distance traveled by the driver was 144 mD. His car did not move between the time t = 4 s and t = 12 s.

26. The velocity-time graph below shows the movement of an object.Graf halaju-masa berikut menunjukkan pergerakkan suatu objek.

Which acceleration-time graph below shows the movement of the object?Antara graf pecutan –masa di bawah yang manakah menunjukkan pergerakkan bagi objek itu?

27. Which of the folowing graphs shows a constant velocity ?

45

a/ms-2

t/s

v/ms-1

t/s

a/ms-2

t/s

v/ms-1

t/s


28. Which of the following is true regarding the motion of an object having zero acceleration?

A The object is moving with uniform velocity B The object is moving with minimum velocity. C The object is moving with maximum velocity

29. Which of the following graphs represents a car moving with zero acceleration ?

A

C

D

t/s

t/s

s/m

t/s

s/m

s/m

t/s

s/m

A B

C D

46

Physics Module : Paper 1 (by nick SMSHS)

29. The graph shows the speed of the car at positions P,Q,R,S and T.Graf menunjukkan kelajuan sebuah kereta pada kedudukan P,Q,R,S dan T.

Which part the acceleration of the car is zero ?

Pada bahagian manakah berikut,pecutan kereta itu adalah sifar ?

A. PQB. PRC. QSD. ST

30. Which of the following quantities increase when an object is moving along a straight line with uniform acceleration?

Antara kuantiti berikut, yang manakah bertambah apabila suatu objek bergerak sepanjang satu garis lurus dengan pecutan seragam?

I Distance / JarakII Velocity / HalajuIII Time taken / Masa yang diambil

A I and II onlyB I and III only C II and III only

P

Q

R

S T

V/ ms-1

t/s

47


D I, II and III

31. The table shows mass and velocity for car X, Y and Z. Jadual menunjukkan jisim dan halaju bagi kereta,X, Y dan Z.

Carkereta

Mass (kg) Jisim(kg)

Velocity (ms-1)halaju( ms-1)

X 2 000 5

Y 1 500 3

Z 1 000 7

Which of the following statements is correct? Pernyataan manakah yang benar.

A Car Z has the greatest inertia Inersia kereta Z paling besar

B Car Y has the greatest momentum Momentum kereta Y paling besar

C Car X has the greatest momentum Momentum kereta X paling besar.

D Car Y has the greatest kinetic energy Tenaga kinetik kereta Y paling besar

32. The diagram shows a coin is placed on a cardboard covering the top of a beaker. When the card is quickly pulled horizontally , the coin falls into the beaker.

Which property of the coin makes this possible?

A Density B InertiaC VolumeD Thickness

Coin

Card

Beaker

48


33. Figure shows four blocks of wood stacked on top of each other.

Block Y is suddenly knocked out of the stacks with a hammer. Block X does not follow the direction of movement of block Y because it has

A weight B momentum C inertia D friction

34. “ A heavy lorry is difficult to start moving and difficult to stop it moving”. “ Sebuah lori yang berat sukar untuk memulakan gerakan dan sukar untuk diberhentikan”.

This statement is refers to Pernyataan ini adalah merujuk kepada

A. the concept of balanced force konsep kesaimbangan daya

B. the concept of inertiakonsep inersia

C. the principle of conservation of momentumprinsip keabadian momentum

D. the principle of conservation of energy.Prinsip keabadian tenaga.

35. Diagram shows a pillion rider moving backwards when the motorcycle accelerates.

The backward movement of the pillion rider can be explained by

A the concept of equilibrium of forces

49


B the principle of conservation of momentumC the concept of inertia

36. Diagram (a) and (a) show a consumer shopping in a supermarket. Initially he pushes an empty trolley and later a full trolley. The shopper finds it more difficult to push a full trolley than an empty trolley.

Diagram (a) Diagram (b)

This situation happened because……..

A the inertia of empty trolley is greater than that of full trolleyB the momentum of empty trolley is greater than that of full trolleyC the inertia of the full trolley is greater than that of the empty trolleyD the kinetic energy of the empty trolley is greater than that of the full trolley

37. A fully loaded lorry in motion is difficult to stop because

A it is traveling with high speedB its inertia is very bigC its mass is very bigD the principle of conservation of energy

38. Which object has the largest inertia?

Objek manakah mempunyai inersia paling besar?

A B

Mass / Jisim = 90 kg Mass / Jisim = 360 kg

Speed / Laju = 20 m s–1 Speed / Laju = 40 m s–1

C D

50


Mass / Mass = 1000 kg Mass / Jisim = 12000 kgSpeed / Laju = 38 m s–1 Speed / Laju = 3 m s–1

39. A student finds it more difficult to stop a moving golf ball which is heavier than a ping-pong ball. The observation can be explained by

A.inertia conceptB.impulsive force conceptC.resultant force concept D.principle of the conservation of momentum

40. A student finds it more difficult to stop a moving golf ball which is heavier than a ping-pong ball. The observation can be explained by concept ofSeorang pelajar mendapati lebih sukar memberhentikan gerekan sebiji bola golf yang berat berbanding dengan sebiji bola ping-pong yang ringan. Pemerhatian ini dapat diterangkan dengan menggunakan konsepA inertia inersiaB impulsive force daya impulsC resultant force daya paduanD conservation of momentum keabadian momentum

41. Inertia balance is used to compare the masses of two different objects by determining the

Neraca inersia digunakan untuk membandingkan perbezaan dua objek dengan menentukan

A amplitude of vibrations of the balance amplitud getaran oleh neraca

B period of vibration of the balance tempoh getaran oleh neraca

C length of the blade of the balance panjang mata neraca

D axis of vibrations of the balance paksi getaran neraca

42. Diagram shows a cat shaking its body from head to tail to shed the water when it gets wet.

The cats shakes water from its coat usingA the concept of inertiaB the concept of equilibrium of forces

51


C the principle of conservation of energyD the principle of conservation of momentum

43. Which of the object has the greatest inertia?

A. B

C. D.

44. What is the property of a body which tends to resist changes acting on it ?

A. Inertia B. ImpulseC. EnergyD. Power.

45. The diagram shows a book falling down from a table.

Which physical quantity of the book increases while it is falling?

A Mass B Kinetic energy

C Acceleration D Potential energy

52

A B C D E


46. The figure shows 5 hanging ball bearings A,B,C, D,E which are of the same mass.

What will happen when ball bearing A is pulled up and then released with velocity, v.

A. velocity of ball bearing A will decrease, velocity of ball bearing D will increase

B. ball bearings B,C,D,E moving with the same velocity, v C. ball bearing A will stop moving, ball bearing E will move with the same velocity, vD. all the ball bearings A,B,C,D,E moving with the same velocity, v

47. Diagram shows two metal spheres, S and R.

4 kg 2kg

Sphere S Sphere R

Which of the following statements is true when S and R are in free fall?

A The velocities of S and R are the sameB The accelerations of S and R are the sameC The momentum of S and R are the sameD The gravitational forces acting on S and on R are the same

53


48. Figure shows a leaf and a stone being released at the same time.Gambarajah menunjukkan sehelai daun dan sebiji batu yang dilepaskan pada masa yang sama.

leaf stone

ground

The stone reaches the ground faster than the leaf becauseBatu tersebut akan mencecah tanah terlebih dahulu daripada daun kerana

A the stone has a greater mass.batu tersebut berjisim lebih besar

B air resistance acted on the stone is smaller.rintangan udara yang bertindak ke atas batu tersebut adalah kecil

C the force of gravity acted on the stone is greater than the force of gravity acted on the leaf.daya tarikan graviti yang bertindak ke atas batu lebih besar daripada

daya tarikan graviti yang bertindak ke atas daunD the force of gravity acted on the leaf is greater than the force of gravity

acted on the stone.daya tarikan graviti yang bertindak ke atas daun lebih besar daripada

daya tarikan graviti yang bertindak ke atas batu

49. Which of the following statement is true?Antara pernyataan berikut yang manakah benar?

A Weight depends on the gravitational field strengthBerat dipengaruhi oleh kekuatan medan graviti

B Weight is a scalar quantityBerat adalah suatu kuantiti skalar

C Weight is measured in kilogramBerat diukur dalam unit kilogram

D Weight is the matter of an object.Berat ialah kuantiti jirim suatu jasad

54

P Q

v

t0

v

t0

v

t0

v

t0

Q

P Q

P

P

QQ

P


50. Diagram shows two steel ball bearings, P and Q, being dropped near the surface of the earth.Rajah menunjukkan dua biji bebola keluli, P dan Q, dijatuhkan berhampiran dengan permukaan bumi.

Which are the correct velocity-time graphs for the motion of P and Q?

Antara graf halaju-masa berikut, yang manakah betul bagi gerakan P dan Q?

A B

C D

51. Figure shows a durian falling from a tree.

What is the physical quantity that is constant when the durian falls?

A. VelocityB. Momentum

55


C. AccelerationD. Kinetic Energy

52. A ball is thrown upwards to a height of h m from the ground. Which of the following is true about the motion of the ball ?

A. Its kinetic energy is constant throughout the motion.B. The time taken to reach a height of h metres is the same as the time taken

to fall from a height of h metres to the ground.C. The gravitational attraction at the height h is zero.

53. A boy of mass 50 kg stands in a lift. His weight reaches 500 N when ……. (given g = 10 N kg-1 )

A. the lift moves upwards with a constant velocity.B. the lift moves downwards with a constant acceleration.C. the lifts fall freely.

54. Which of the following will change when a coconut falls freely?

A Mass B Acceleration C Momentum D Weight

55. Mawi rides his bicycle starting from rest and accelerates at a uniform rate of 0.5 ms-2

What is the time taken to travel a distance of 100 m?

A 5.0 s B 10.0 s C 15.0 sD 20.0 s E 25.0 s

56. David Beckham kicks a ball from a free kick point with a speed of 10 ms -1 and the ball reaches the goal post after 2 s. If the distance from the free kick point to the goal post is 12 m, calculate the speed of the ball when it reaches the goal post.

A 1.5 ms-1 B 2.0 ms-1 C 2.5 ms-1

100 m

u = 0 t = ?

56


D 3.0 ms-1 E 3.5 ms-1

57


57. An object was released at a height of 50 m. What is the time taken to reach the ground ?Satu objek dilepaskan pada ketinggian 50 m. Berapakah masa yang diambil untuk sampai ke lantai?

A 1.0 s B 2.2 s C 3.2 sD 5.0 s E 100 s

58. Diagram shows a man releases a stone into a well. If the distance between the top of the well and the water surface is 30 m, what is the time required for the stone to reach the surface of the water?

A 6.12 s B 3.65 sC 4.27 s D 2.45 s

59. Figure shows a high-jumper falls on a thick mattress.

The purpose of putting a mattress after the bar is to

A. decrease the impulsive forceB. decrease the stopping time of the high-jumper.C. decrease the velocity of the high-jumper.

60. Impulsive force is defined as

A. The change in impulseB. The difference in pressureC. The rate of change in momentum

30 m

58

Air flowAliran udara

Electric fanKipas elektrik

TrolleyTroli


61. Diagram shows a trolley with an electric fan.

Rajah menunjukkan sebuah troli dengan kipas elektrik.

What happens to the trolley when the electric fan is switched on?

Apakah yang berlaku kepada troli itu apabila kipas elektrik dipasang?

A Moves to the right / Bergerak ke kananB Moves to the left / Bergerak ke kiriC Remains stationary / Kekal pegunD Moves to the right and to the left / Bergerak ke kanan dan ke kiri

62. When the hammer hits the release spring in diagram below, both of the trolleys,P and Q move out at opposite direction.Apabila tukul diketuk pada pelepas spring dalam rajah di bawah, kedu-dua troli P dan Q bergerak dalam arah bertentangan..

Which of the following caused both of the trolleys reached the wooden block at the same time?Antara berikut, yang manakah menyebabkan kedua-dua troli sampai ke bongkah kayu pada masa yang sama?

Mass of trolley P Mass of trolley Q Distance of P Distance of QJisim troli P Jisim troli Q Jarak P Jarak QA 0.4kg 0.8kg 0.2m 0.4mB 0.4kg 0.8kg 0.4m 0.8mC 0.8kg 0.4kg 0.8m 0.4mD 0.8kg 0.4kg 0.4m 0.8m

63. Figure shows two identical trolleys joined together on a smooth horizontal

59


surface. When the pin is hammered in, the trolleys move in opposite directions.

Which of the following quantities are the same for both trolleys?

A Velocity C MomentumB Acceleration D Kinetic energy

64. The linear momentum of an object of mass m, moving with a velocity, v is defined as

A. The product of its mass and its velocityB. The product of its displacement and its time takenC. The product of its mass and its acceleration

65. The Principle of Conservation of Momentum states that

A. The total energy of a closed system is constant, if there is external force acting on it.

B. The total energy of a closed system is constant, if there is no external force acting on it.

C. The total momentum of a closed system is constant, if there is no external force acting on it.

D. The total momentum of a closed system is constant, if there is external force acting on it

66. Diagram shows two identical trolleys M and N moving towards one another.

M NThey collide and come to rest at the point of impact. From this observation we can conclude that the trolleys have

A. equal masses C. equal and opposite velocitiesB. equal kinetic energy D. equal and opposite momentum

60


67. A bullet of mass 10 g is fired from a gun of mass 490 g. The bullet leaves the gun with a speed of 120 m s-1. Find the initial speed of recoil of the gun.

A. 2.4 m s-1 D. 8.8 m s-1

B. 4.8 m s-1 E. 9.0 m s-1

C. 7.4 m s-1

68. A man of mass 50 kg stands on a stationary boat of mass 25 kg. Figure shows him jumping out of the boat on to a jetty at a velocity 4 ms-1.

Calculate the velocity of the boat as the man jumps.

A 2 ms-1

B 4 ms-1

C 6 ms-1

D 8 ms-1

E 10 ms-1

69. The diagram shows a squid moving forward by discharging a jet of water from its body.

The forward movement of the squid can be explained by

A conservation of energyB Newton’s First Law of motionC conservation of momentumD Newton’s second law of motion

v = 4 ms-1

61


70. Which of following statements best describes an elastic collision between two objects?

A Only momentum is conserved.B Only kinetic energy is conserved.C Momentum and kinetic energy are conserved.D Total energy, momentum and kinetic energy are conserved.

71. Diagrams shows a karate – do presenter moves his hand so fast and stops it when his hand touches the brick so that

A the collision time will be longerB the impulsive force will increaseC the bricks will crack and break together

72. In an inelastic collision, which of the following quantity remains constant before and after the collision?Dalam perlanggaran tak kenyal, kuantiti yang manakah tidak berubah sebelum dan selepas perlanggaran.?

A Total acceleration / jumlah pecutanB Total velocity / jumlah halajuC Total momentum / jumlah momentumD Total kinetic energy / jumlah tenaga

73. The effect of impusive force can be reduced by A increasing the time of contact B increasing the velocity of impact C increasing the mass of colliding object D increasing the hardness the crushed surface.

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R


74. Diagram (a) shows a frog of mass 0.1 kg stands on a stationary leaf of mass 0.01 kg.


When it jumps out of the leaf at a velocity of 2 ms-1, calculate the velocity of the leaf as the frog jumps.

A 1 ms-1 B 2 ms-1 C 10 ms-1

D 20 ms-1 E 25 ms-1

75. Which of the following games does not require impulsive force

A table tennis B football C golf D badminton E dart

76. Diagram shows a softball player catching a fast-moving ball.

In which direction should the player moves his hand in order to decrease the impulsive force before the ball stops?

A P B Q C R D S

leaf

frog

water

2 ms-1

P

QS

63


77. The following statements are true about impulse and impulsive force except

A Impulse is the rate of change of momentum B Both impulse and momentum have the same unit. C Impulsive force increases when the time of impact decreases. D The car bumpers are made easily folded to reduce impulsive force

78. Which of the following situation is not a benefit of impulsive force?Antara situasi berikut yang manakah tidak menunjukkan kebaikan daya impuls?

A Hammer a nail into a woodMenukul paku ke dalam kayu

B Hit a ball using a racketMemukul bola menggunakan rakat

C Collision between two vehiclesPerlanggaran diantara dua kenderaan

D Pushing a needle to sew a button onto a shirtMenolak jarum bagi menjahit butang baju

79. Why are the front and rear sections of a car are designed to crumple easily ?Mengapalah bahagian hadapan dan belakang kereta direka bentuk supaya mudah remuk ?

A To increase the time of impactUntuk memanjangkan masa pelanggaran

B To decrease the momentum Untuk mengurangkan momentum

C To increase the friction Untuk menambahkan geseran

D To decrease the impulseUntuk mengurangkan impuls

80. Impulsive force is defined asDaya impuls didefinisikan sebagai

A the change in impulseperubahan impuls

B. the difference in pressureperbezaan tekanan

C. the rate of change of momentumkadar perubahan momentum

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81. The advertisement of a car manufacturer states that their car has bumpers fitted with shock absorbers. What is the additional advantage of this feature?

A To ensure that the car is not smashed up in an accident.B To ensure that the car will decelerate in an accident.C Guarantees that all passengers are not injured in an accident.D To increase the time interval of interaction in a collision so that the impulsive force can be minimized.

82. A ball is being kicked by a force of 10 N. If the force is exerted in 0.2 s, what is the impulse experienced by the ball ? Sebiji bola ditendang dengan daya 10 N. Jika daya dikenakan dalam masa 0.2 s,

berapakah impuls yang dialami oleh bola? A 0.8 N s B 2.0 N s C 10.2 N s D 30.0 N s

83. In sports, thick mattress is used in events such as the high jump and pole vaulting. What is the function of the mattress?.

A To reduce the collision time between the athletes and the mattressB To reduce the change of momentum of the athletes when he hits the mattressC To reduce the impulsive force acting on the athletes when he hits the mattress.

84. Diagram show a car.

The front and back parts of a car are designed to crumple easily during a crash so that

A the collision time will be longerB the impulsive force will increaseC prevent the passengers from being thrown forwards

85. Unit for impulse is same with unit for Unit impuls adalah sama dengan unit

A Force C EnergyDaya Tenaga

B Momentum D PowerMomentum Kuasa

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Crumple zoneZon remuk


86. Diagram shows the condition of a car after an accident.Rajah menunjukkan keadaan sebuah kereta selepas satu kemalangan.

The function of the crumple zone of the car is to reduce the

Fungsi zon remuk kereta itu adalah untuk mengurangkan

A inertia / inersiaB momentum / momentumC impulsive force / daya impulsD gravitational force / daya graviti

87. The diagram shows a car with a bumper fitted with shock absorbers.

The advantage of using the bumper fitted with shock absorbers is

A to ensure that the car will decelerate in an accident.B to minimise the impulsive force during an accident.C to ensure that the car is not smashed in an accident.

Bumper

66

5 N 5 N

5 N 5 N

5 N

5 N 5 N

4 N

4 N

5 N 5 N

5 N

5 N


88. Which of the following is not a safety feature installed in a vehicle ?

A Engine capacityB Automatic air bagC Collapsible steering wheels D Shatterproof windscreen glass

89. An object is moving with zero resultant force. Which of the following inference is not true?

A. Its velocity is constantB. Its acceleration is zeroC. Its displacement is zeroD. It has encountered a constant resistance.

90. Which of the following best describe the weight of an object?

A. Weight is a gravitational force acting on an objectB. Weight is a scalar quantityC. Weight is measured in kilogramD. Weight is matter quantity in an object

91. In which of the following cases, the net force acting on the object is not zero ?

A

B

C

D

67

R P

m = 2 kg


92. Two teams, Team A and Team B are pulling in opposite direction on a rope. The forces acting on the rope are shown in the diagram.Dua pasukan, Pasukan A dan pasukan B sedang menarik tali pada arah yang bertentangan. Daya yang dikenakan pada tali adalah seperti yang ditunjukkan pada rajah.

What is the resultant force acting on the rope and its directions? Berapakah daya paduan yang bertindak ke atas tali dan apakah arahnya?

A 150 N acting towards the team A 150 N bertindak pada arah pasukan A B 150 N acting towards the team B 150 N bertindak pada arah pasukan B

C 350 N acting towards the team A 350N bertindak pada arah pasukan A D 350 N acting towards the team B 350 N bertindak pada arah pasukan B

93. Diagram shows a block of wood moving with an acceleration, a = 3 ms-2.

Which of the following are the values of the forces P and R ?

ABCD

450 N600 N

rope

Team APasukan A

Team BPasukan B

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P / N R / N8 610 711 56 6

F

4 N

600

Rough surface


94. The diagram shows a steel block is pulled by a force of F moves with a constant velocity and encounters a friction of 4 N.Rajah menunjukkan sebungkah besi ditarik oleh daya F dengan halaju seragam dan menghasilkan daya geseran bernilai 4 N.

What is the value of force, F ? Berapakah nilai daya, F ?.

A. 0.5 NB. 3.5 NC. 5.5 ND. 8.0 N

95. A car of mass 800 kg is accelerating at 2.5 ms-2. If the total drag force on the car is 300 N, what is the forward force exerted by the car engine ?

A 1100 NB 1700 NC 2000 ND 2300 N

96. Which of the following situations is in equilibrium force? Antara situasi berikut yang manakah berada dalam keseimbangan daya?

A A swing cradleAyunan buaian

B A free falling objectsObjek yang jatuh bebas

C A baseball hit with a batPemukul yang memukul bola besbal

D A trolley moving with uniform velocity on a friction compensated runawayTroli yang bergerak dengan halaju seragam di atas landasan terpampas geseran

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97. An object of wooden block of weight 30 N ( mass 3.0 kg ) is being pulled upward by a string which passes over a smooth pulley.

If the object accelerates upwards at 2 ms-2, what is the tension, T, in the string ?

A 24 NB 30 NC 36 ND 40 N

98. The Figure shows forces, F1 and F2 , exerted on a wooden block placed on a table surface. The friction between the block and the table surface is 2 N.

Which pair of forces F1 and F2 causes the wooden block to move with an acceleration?

F1 / N F2/ N

A 7 9B 5 7C 6 4D 3 2E 4 1

F1 F2

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99. The diagram shows a wooden block pulled by a force of 10N at an angle of 40o above the horizontal floor.

If the wooden block is pulled through a distance of 5m, how much work is done on the wooden block?

A 7.66 JB 18.8 JC 24.4 JD 38.3 JE 50.0 J

100. The figure shows an aircraft flying in the air.Gambarajah menunjukkan sebuah kapal terbang sedang terbang di udara.

The aircraft will accelerate if Kapal terbang tersebut akan memecut jika

A lift weightdaya angkatan > berat

B Thrust Liftdaya ke depan > daya angkatan

C Lift Air frictiondaya angkatan > rintangan udara

D Thrust Air frictiondaya ke depan > rintangan udara

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F

4 N

600

Rough surface

2 kg

K

L M N

Friction compensatedrunway

Rough surface Smooth surface


101. A diagram shows a steel block is pulled by a force of F moves with a constant velocity and encounters a friction of 4 N, calculate the value of F ?

A. 0.5 N C. 5.5 NB. 3.5 N D. 8.0 NC. 4.0 N

102. Figure shows the path taken by a trolley. The trolley passes through K with a certain velocity. KL, LM and MN are all equal in length.

Which of the following is true of the motion of the trolley from K to N?

103. A constant force , F acts on a block placed on a smooth surface as shown.

The block will move with

A uniform speedB uniform accelerationC gradually increasing acceleration

F

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Path taken MotionA K to L Uniform velocityB L to M AccelerationC M to N Deceleration


104. Which diagram correctly shows the addition of the 3 N and 4 N forces?

A 5 N

3 N

4 N

B 5 N

3 N

4 NC

5 N 3 N

4 N

D 5 N 3 N

4N

105. The diagram shows A parachutist of mass 60 kg is descending at a uniform velocity of 4 ms-1

. The resultant force acting on the parachutist is

A zeroB 240 N vertically downwardsC 240 N vertically upwardsD 600 N vertically downwardsE 600 N vertically upwards

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106. Which of the following systems will produce maximum acceleration?

107. Figure shows a boy standing on a weighing machine in a stationary lift.

When the lift moves down and accelerates, what will be the reading on the weighing machine?A Less than 500 N.B More than 500 NC No change

108. A force of 80 N pulls a load of 5 kg through a smooth pulley.

500 N

A. m

12 N 8 N

B. m 18 N 6 N

C. m 20 N

D. m 15 N 10 N

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What is the acceleration of the load ?

A 5.0 ms-2

B 6.0 ms-2

C 8.0 ms-2

D 10.0 ms-2

E 16.0 ms-2

109. Diagram shows a trolley of mass 4.0 kg is placed on a rough table and being

pulled by a force of 4.0 N. The trolley moves at constant velocity. Calculate the frictional force.

4.0 N

Frictional forceA 2 NB 4 NC 8 ND 16 NE 40 N

110. Figure shows a picture hanging on a wall.

5 kg

80 N

75


Which vector diagram represents the forces, T1, T2 and W that act on the picture?

111. Diagram (a) shows a horse pulling a carriage.

Tension, T2

StringTension, T1

Weight, W

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Diagram (b) shows another horse of the same strength is added.


What happens to the acceleration of the carriage when two horses are pulling the same carriage?A It decreasesB It increasesC It is constant

112. A customer pushes a trolley of mass m kg up a smooth inclined plane. A horizontal force of F N is applied to the trolley which moves a distance of s metres.

The work done by the customer isA mghB FsC Fs sin θD Fs cos θ

113. A student is pulling a trolley with an iron chain which makes an angle of 60° with the horizontal.

If the tension of the spring is 4 000 N , what is the horizontal force? A 1 000 N B 2 000 N C 2 400 ND 3 464 N. E 4 000 N

114. Figure shows a box being pulled by a force, F which makes an angle, θ with

77


the horizontal surface.

θ

The friction against the motion of the box is G. What is the resultant force that causes the box to move?

A F cos θ – GB F cos θ + GC F sin θ + GD F sin θ – G

115. Diagram shows a boy standing on a weighing balance in a stationary lift. The reading of the spring balance is 600 N

What is the reading of the balance when the lift moves up with an acceleration of 2 ms-2?

A 300 N B 480 N C 600 ND 720 N E 1200 N

116. The diagram shows an aeroplane flying at a constant velocity.

Force, F

Friction force, G

box

78


Which relationship between the forces is true?

A U = WB F > GC U < WD F = G

117. Diagram shows a parachutist in four positions after he jumps from a high hot air balloon.

At which position does he experience unbalanced forces?

A not yet moving hot air balloon at constant height

B accelerating

C velocity constant

D at rest

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F

Weighing scaleAlat penimbang

Reading / Bacaan = W


118. Diagram (a) shows a girl standing on a weighing scale with her hands on a table. The reading of the scale is W.

Rajah (a) menunjukkan seorang budak berdiri di atas sebuah alat penimbang dengan tangannya di atas sebuah meja. Bacaan penimbang itu ialah W.


What would be the reading of the scale if she were to press the table with a force F downwards as shown in Diagram (b)?

Apakah bacaan penimbang itu jika dia menekan meja dengan satu daya, F ke bawah seperti ditunjukkan dalam Rajah 6.2?

A W B F C W + FD W - F

119. Diagram shows a block of mass 2 kg slides from rest through a distance of 20 m down a frictionless slope.

DiagramWhat is the kinetic energy of the block at the bottom of the slope?(The acceleration of free fall is 10 ms-2)

A 20 J B 40 J C 200 JD 400 J E 2000 J

120. The potential energy of an object depends on all of the following except

80

Smooth inclined planeSatah condong licin

Box / Kotak

0

PE

KE0

PE

KE

0

PE

KE0

PE

KE


A the mass of an objectB the acceleration of gravityC the velocity of an object

D the height of an object.

121. Diagram shows a box sliding down a smooth inclined plane.

Rajah menunjukkan sebuah kotak menggelongsor menuruni satu satah condong yang licin.

Which graph shows the relationship between the potential energy (PE) and kinetic energy (KE) of the box as it moves down the plane?

Graf yang manakah menunjukkan hubungan antara tenaga keupayaan (PE) dan tenaga kinetik (KE) kotak itu ketika sedang bergerak menuruni satah itu?

A B

C D

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122. Diagram shows a man is pilling a rope vertically downwards to lift a load of 15 kg on the other end through a vertical height of 2 m.Rajah menunjukkan seorang lelaki menarik tali ke bawah untuk mengangkat beban sebanyak 15 kg setinggi 2 m.

What is the work done?Berapakah kerja yang telah dilakukan?

A 7.5 JB 17 JC 30 JD 150 JE 300 J

123. Figure shows a car moving along a straight road. The total energy input from the petrol is 80 kJ. During the journey the car has wasted about 50 000J of energy.

What is the efficiency of the car?

A 25.0% B 37.5% C 45.0% D 62.5%

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124. Figure shows a pile driver at a velocity of 20 ms-1 driving a foundation pile into the ground. The pile driver and the foundation pile moves together after hitting it.

Determine the velocity of the foundation pile immediately after being hit by the pile driver.

A 30.00 ms-1

B 14.00 ms-1

C 4.28 ms-1

D 0.53 ms-1

E 0.43 ms-1

125. A ball is thrown vertically upwards.Neglecting air resistance, which statement is correct?

A The kinetic energy of the ball is greatest at the greatest height attained.B By the principle of conservation of energy, the total energy of the ball is

constant throughout its motionC By the principle of conservation of momentum, the momentum of the ball

is constant throughout its motion.

Piledriver 150 kg

Foundation pile550 kg

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126. Diagram shows a car is driven along a level road. The total energy input from the petrol is 60 kJ, and the car wastes 45 kJ of energy

What is the efficiency of the car?

A 15 %B 25 %C 45 %D 75 %E 105 %

127. Hydroelectric, tidal and fossil fuels are three sources of energy.

Which of these are renewable energy sources?

Hydroelectric Tidal Fossil fuelsA No Yes YesB No No YesC Yes No NoD Yes Yes No

128. Figure shows a ball with mass 2 kg slides down a smooth curved ramp from point P to Q. What is the speed of the ball when it reaches point Q ?

A 12.6 ms-1

B 8.9 ms-1

C 6. 3 ms-1

D 4.0 ms-1

P

Q

0.8 m

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129. Figure shows a cradle with spring x.

Spring x can hold a maximum load of 5 kg. Which of the following ways is used so that the cradle can hold a baby of 7 kg ?

A. Change with a spring of greater diameterB. Increase the length of the springC. Add one spring and arrange in series.D. Add one spring and arrange in parallel.

130. Figure (a) shows a spring P extends by 5 cm when it hung with a 0.5 kg weight. Figure (b) shows four springs P are arranged in a system and it hung with a 1.0 kg load.

What is the total extension of the spring system?

A 5.0 cmB 10.0 cmC 15.0 cmD 20.0 cmE 25.0 cm

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400 g

A B C D

400 g

400 g400 g


131. Four arrangements A, B, C and D are made of identical springs. Each spring extends by 4 cm when a 200 g load is hung at its end. Which arrangement produces the largest extension?

Empat susunan A, B, C dan D adalah terdiri daripada spring yang sama. Setiap spring meregang sebanyak 4 cm apabila satu beban 200 g digantung pada hujungnya. Susunan yang manakah menghasilkan regangan yang terbesar?

132. A spring extends by 6 cm when a load of 30 N is suspended from it.

Diagram 22

Two identical springs are connected as shown in Diagram 22 to carry a 30 N load. What is the extension of the spring system?

A 3 cmB 5 cmC 6 cmD 12 cmE 15 cm

133. The elastic constant of a spring, k can be increased by

A. reducing the length of the springB. reducing the diameter of the springC. using a thinner wireD. using a low strength metal

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134. Diagram shows a system of three identical springs. The original length of each spring is 10 cm. It is stretched to 13 cm when it is loaded with mass of 50 g.Rajah menunjukkan satu system tiga spring yang sama. Panjang asal setiap spring ialah 10 cm. Spring itu akan memanjang kepada 13 cm apabila digantung beban 50 g.

What is the total length of spring, X cm ?Berapakah jumlah panjang spring, X cm ?

A 26 cmB 29 cmC 32 cmD 39 cm

135. The diagram shows three identical springs.

The original length of the spring is 10.0 cm. Each spring produces an extension of 3.0 cm when weighted with a load of 10 N. What is the value of x?

A 9.0 cm B 11.0 cm C 15.0 cmD 19.0 cm E 25.0 cm

10.0 N

x

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136. Diagram shows the relationship between the force applied and the corresponding extensions of spring P and spring Q. Which of the following statements about spring P and Q is true?

Spring P Spring Q

A Spring P is more difficult to extendB For the same extension, spring P needs a lower forceC More energy has to be used for spring Q in order to produce the same

amount of force

137. Figure shows a 6 N load attached to a system made up of two identical springs. The original length of each spring is 10.0 cm.

What is the force constant of each spring?

A 1.5 N cm-1

B 2.0 N cm-1

C 3.0 N cm-1

D 4.0 N cm-1

11.5 cm

6 N

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Physics Module Forces & Motion

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