thequarkyteacher.files.wordpress.com€¦ · Web view1.23know that the initial linear region of a force-extension graph is associated with Hooke’s law. 1.24describe elastic behaviour

Edexcel ScienceiGCSE Physics

P. Challenging Forces

2019-2020

Name:________________Physics Teacher:______________

House CG Test Score

Year 11 (d)

Specification Checklist

1.01 use the following units: kilogram (kg), metre (m), metre/second (m/s), metre/second2

(m/s2), newton (N), second (s) and newton/kilogram (N/kg)

1.03 plot and explain distance−time graphs

1.06 know and use the relationship between acceleration, change in velocity and timetaken:

acceleration= change∈velocitytime taken

a= v−ut

1.07 plot and explain velocity-time graphs

1.08 determine acceleration from the gradient of a velocity−time graph

1.09 determine the distance travelled from the area between a velocity−time graph and the time axis

1.1 use the relationship between final speed, initial speed, acceleration and distance moved:

(final speed)2 = (initial speed)2

+ (2 × acceleration × distance moved)

v2=u2+2×a×s

1.11 describe the effects of forces between bodies such as changes in speed, shape or direction

1.12 identify different types of force such as gravitational or electrostatic

1.13 understand how vector quantities differ from scalar quantities

1.14 understand that force is a vector quantity

1.15 calculate the resultant force of forces that act along a line

1.17 know and use the relationship between unbalanced force, mass and acceleration:

force = mass × acceleration

F = m × a

1.21 describe the forces acting on falling objects (and explain why falling objects reach a terminal velocity)

1.22 practical: investigate how extension varies with applied force for helical springs, metal wires and rubber bands

Challenging Forces – Science (Physics) 2

1.23 know that the initial linear region of a force-extension graph is associated with Hooke’s law

1.24 describe elastic behaviour as the ability of a material to recover its original shape after the forces causing deformation have been removed

Key Words

Key Word Image Definition

Air Resistance The Force acting against your movement in air. Caused by collision with air particles.

Acceleration The rate of change of speed.

Balanced Force

The forces on an object that cancel each other out. No resultant force.

Elastic A material that will return to its original shape after being stretched or compressed.

Electrostatic The force of attraction or repulsion between positive and negative objects.

Extension The amount an object has been stretched by.

GradientThe steepness of a line. Calculated by

Change∈y valueChange∈x value .

Gravitational force.

This is weight. Gravity is a field that causes objects to weigh something.

Limit of Proportionality

The point where a material no longer obeys Hooke’s Law.

Newton The unit for Force. [N]

Resultant Force

The overall Force remaining after you have added and subtracted all the forces from each other.

Scalar Something with only magnitude. Just a number.

Terminal Velocity

The maximum speed of an object. When the drag and the propelling force are balanced.

Tension The force pulling something to stretch it. For example, tension in a rope during a tug of war.

Upthrust An upward force on an object in a liquid or gas. This force is caused by the particles wanting to get back underneath the object that moved them.

Vector Something with both direction and magnitude. For example, a Force.


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https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwjppvDVvtvdAhUJ2xoKHfbYD1UQjRx6BAgBEAU&url=https://ubisafe.org/explore/frication-clipart-balanced-force/&psig=AOvVaw3sn1hXV5ntBUbpBSKPtqv6&ust=1538148167273834

https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwj6zfSrv9vdAhURyYUKHYHyCnsQjRx6BAgBEAU&url=https://pixabay.com/en/kilogram-mass-weight-10-gravity-147629/&psig=AOvVaw3IR0SvuhFhDiBjaFaY2TzE&ust=1538148369539183

https://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwiZuejFv9vdAhXlzoUKHVamBYcQjRx6BAgBEAU&url=http://getdrawings.com/skydiving-clipart&psig=AOvVaw1bUkk3Jg0RZ3Hyq0e0JTC7&ust=1538148420846158

Weight The downward force on an object. Due to gravity pulling it towards the earth. This can be different on different planets.


1: Balanced and Unbalanced Forces

Starter Task: What do you know about Forces?

On the mind map below can you add everything you already know about Forces? Be ready to share your ideas with the class.


FORCES

Learning Outcomes:

1. Describe Force as a vector quantity that has magnitude and direction2. Describe the difference between forces which are balanced and those which are

unbalanced3. Calculate the resultant force along a line

Vectors vs. Scalars

Examples

Vector Scalar

Key Ideas

1. Scalars are quantities that have magnitude (size) only.2. Vectors are quantities that have magnitude (size) and direction. 3. Force is a vector quantity. 4. We can represent Force as an arrow on a diagram to illustrate direction and size

(length).


Balanced and Unbalanced Forces (Resultant Forces)

Key Ideas

1. Force is measured in Newton’s [N]. 2. When forces are balanced the object will move at a constant speed (already moving)

or will not move at all (remain stationary)3. When forces are unbalanced the object will change shape, speed or direction. 4. When forces are balanced the resultant force is zero. 5. When forces are unbalanced the resultant for is non-zero.

Worked Examples – Resultant Force

What is the resultant force on the following objects? Represent it on the second trolley.


Resultant force

55N

Worksheet – Calculating the Resultant Force

In each of the examples below calculate the resultant force and state its direction.

1. 2.

Resultant Force = ……. ………... Resultant Force = ……. ………...

3. 4.


5. 6.


7. 8.



4N 10N

92N 110N600N 124N

25N 13N

125N

72N

5.2N

11.3N

50N 50N

103N

34N

64N 22N

60N

60N

2: Newtons 2 nd Law

Knowledge and Understanding CheckCan you answer the following questions using your knowledge from last lesson and from Shell?

1. If a box is being pulled to the right with 15N and to the left with 8N, what is the resultant force on the box?

……………………….[3]2. Give an example of a vector quantity.

……………………………………………………………… [1]

3. Sketch a box below that is being acted upon by 3 forces that when added together give a resultant force of 0N.

[3]

4. Calculate the resultant forces on the objects below:

[4]

5. What is the mass of an object that weights 635N?

……………………….[3]

[Score /14]


10N 12N 1.2N 4.5N

Learning Outcomes:

1. Rearrange and use the equation:F=m×a

2. Describe Newton’s 2nd Law of motion3. Explain how an object reaches terminal velocity.

Force, Mass and Acceleration

Key Ideas

1. An object will not change its velocity unless an unbalanced force acts upon it. 2. Force, mass and acceleration are linked in the equation:

Force=mass×acceleration3. This means that if the same unbalanced force was applied to two objects of different

masses. The object with the smaller mass would accelerate more.

Worked Examples

1. What unbalanced force is required to accelerate a 6kg mass by 2m/s2?

2. An object experiences an unbalanced force of 16N and accelerates at 4m/s2. What must the mass of the object have been?

Worksheet – Newton’s 2 nd Law


Complete the questions below using the equation you have just learnt. You must show all of your working [equation, substitution, solution and units]

1. How much force is required to accelerate a 2 kg mass at 3 m/s2?

…………………..


…………………..


…………………..

4. Given a force of 100 N and an acceleration of 10 m/s2, what is the mass?

…………………..


…………………..

6. What is the acceleration of a 10 kg mass pushed by a 5 N force?

…………………..



…………………..

8. What is the acceleration of an 18 kg mass pushed by a 9 N force?

…………………..9. Find the acceleration of the 2 kg block in the following diagram.

…………………..10. Find the acceleration of the 500g block in the following diagram

…………………..11. If a 600g object is accelerating at 2m/s2, what is the unbalanced force acting on it?

…………………..12. Given a force of 560 kN and an acceleration of 3 m/s2, what is the mass?

…………………..

Terminal Velocity


Key Ideas

1. At the point of release the only force acting on an object is weight. 2. This unbalanced force causes the object to accelerate3. As the object accelerates the drag force begins to increase4. As the object gains speed the drag force increases5. Eventually the drag force is equal in magnitude to weight and the forces are

balanced. This means there will be no acceleration. 6. This causes the object to travel at a constant speed which we call terminal

velocity.

Worksheet: Terminal Velocity


Here is the velocity data for a base jumper.

1. Plot an appropriate graph and draw a smooth curve that passes through each point [5]

Time [s] 0 5 10 15 20 25 30 35 40 45 50 55 60

Velocity [m/s] 0 28 43 48 50 50 50 49 12 10 10 10 0

2. Label the following onto the graph [5]:

Acceleration, Terminal velocity, Parachute opens, Deceleration, Speed that jumper hit the ground.

3. Describe how the forces on the base jumper change during their journey. [5]

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

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

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

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

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

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

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


3: Hooke’s Law and Elastic Behaviour


1. An object with a mass of 15kg is accelerating at 4m/s2. What unbalanced force must be acting on the object?

……………………….[3]2. A resultant force of 250N acts on an object with a mass of 500g. What acceleration

will this cause?

……………………….[3]

3. What is the weight of an object with a mass of 4kg?

……………………….[3]


……………………….[3]

5. On a far distance planet a 600kg object weighs 150N. What is the value of g on this planet?

……………………….[3]

[Score /15]


Learning Outcomes:

1. State Hooke’s Law and represent it on a force-extension graph2. Describe elastic behaviour and explain how this could be identified on a

force-extension graph3. Describe a practical to investigate the force applied to an object affects it’s

extension

Pd1: Investigating Hooke’s Law

In this investigation you are going to be measuring how extension varies with Force applied.

Answer the questions below before you begin theinvestigation!

1. You will be given the value of your mass is kg. How do I turn this into a force [N]?

2. You will have to measure the extension of your spring rather than the length. Draw a diagram below to explain how to measure extension.

Method

1. Set up your apparatus as shown in the diagram.

2. Measure the length of your spring without any hanging masses.

3. Hang a mass of 100g on the spring4. Measure the new length of the spring5. Work out the extension of the spring6. Repeat steps 3-5 for more masses

(increments of 100g)7. Take note of your results in the table.

Original Length of Spring =


Health and Safety Check!

I will wear goggles when using springs

Results

Mass [g] Mass [kg] Force [N] Extension [cm]

0

100

200

300

400

500

600

700

800

Now plot your results below (extension on the x-axis, Force on the y-axis)

Describe the relationship between force and extension. [2]

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


Graph Checklist

Axes Labels (inc. units)

AppropriateScale

Points Plotted

Line of BestFit

Hooke’s Law

Key Ideas

1. Hooke’s Law: extension is directly proportional to the force applied. 2. It can be represented as a straight line through the origin on a Force-Extension

Graph3. We call the point when an object stops obeying Hooke’s Law the limit of

proportionality.

Elastic Behaviour

Key Ideas

1. Elastic behaviour is the ability of a material to recover its original shape after the forces causing deformation have been removed.

2. We say an object has past it’s elastic limit when it stops behaving elastically (will not return to it’s original shape.


Pd2: Elastic Behaviour

In this investigation you are going to be measuring how extension varies with Force applied.

This experiment is similar to the previous. New instructions are labelled with an (*).

Method

1. Set up your apparatus as shown in the diagram.

2. * Mark your elastic band in two places 3. Measure the distance between the points

on your elastic band* without any hanging masses.

4. Hang a mass of 100g on the elastic band5. Measure the new length of the elastic band6. Work out the extension of the elastic band7. Repeat steps 3-5 for more masses

(increments of 100g)*Do not take masses off in betweenreadings!

8. *Now unload the elastic band one massat a time

9. *Measure the extension of the elastic bandeach time.


Health and Safety Check!

I will wear goggles when using springs

Elastic under tension - be careful (may break)

Elastic band/lace

100g masses

Results – Elastic Band

Mass [g] Mass [kg] Force [N]Extension

[cm] Loading

Extension [cm]

Unloading

0

100

200

300

400

500

Now plot your results below (extension on the x-axis, Force on the y-axis) Plot Loading and Unloading in different colours!

Is the elastic band behaving elastically? Explain your answer.

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

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

Does the Elastic Band obey Hooke’s Law? ………………………..


Graph Checklist

Axes Labels (inc. units)

AppropriateScale

Points Plotted

Line of BestFit

4: Equations of Motion


1. An object with a mass of 26kg is accelerating at 2.5m/s2. What unbalanced force must be acting on the object?

……………………….[3]2. Give an example of a scalar quantity.

……………………………………………………………… [1]

3. Draw a Force-Extension graph for an object which obeys Hooke’s Law

[3]

4. Calculate the resultant forces on the objects below:

[4]


……………………….[3]

[Score /14]


Learning Outcomes:

1. Rearrange and use the equation:

Acceleration=Change∈VelocityTimeTaken to calculate Acceleration.

2. Identify the different variables in the equation:v2=u2+2as

3. Rearrange and use the equation:v2=u2+2as

Calculating Acceleration

Key Ideas

1. Acceleration, change in speed and time taken are linked in the following equation:

Acceleration=Change∈VelocityTimeTaken

2. If the acceleration is negative the object is slowing down (decelerating)

Worked Examples

1. What is the acceleration of an object that goes from rest to 60 m/s in 5s?

2. What is the final speed of an object that accelerates from rest at 12 m/s2 for 5s?


Worksheet – Acceleration


1. Calculate the acceleration of a car that moves from rest (0 m/s) to 10 m/s in 5 seconds.

…………………..

2. Calculate the acceleration of a train that move from rest to 20 m/s n 80 seconds.

…………………..

3. Calculate the acceleration of a cyclist that moves from rest to 8 m/s in 2 seconds.

…………………..

4. How long does it take a cyclist to reach 10 m/s from rest if they are accelerating at 2m/s2?

…………………..

5. How long does it take a rocket to reach 1000 m/s from rest if it is accelerating at 50 m/s2?

…………………..

6. A car accelerates at 5 m/s2 for 25 seconds. What is it’s change in speed?

…………………..


7. A train accelerates at 4 m/s2 for 1 minute. What is it’s change in speed?

…………………..

8. Calculate the acceleration of a car that moves from 10 m/s to 22 m/s in 4 seconds.

…………………..

9. Calculate the acceleration of a train that changes from 5 m/s to 20 m/s in 4 seconds .

…………………..

10. What is the final velocity of a car that accelerates for 2 minutes at 1.5m/s2?

…………………..

11. What is the final velocity of a cyclist after 5 seconds if they accelerate at 3m/s2 from a speed of 4m/s?

…………………..

12. What is the deceleration of a car that takes 30 seconds to stop when travelling at 26m/s?

…………………..


Using v2=u2+2as

Key Ideas

1. Final speed, initial speed, acceleration and displacement are linked by the following equation:v2=u2+2as

2. Displacement is the vector version of distance 3. Acceleration must be constant to use this equation.4. Make sure you are confident rearranging this equation.

Worked Examples

1. A cylinder containing Miss Jayne’s favourite herbal tea bags is dropped from a helicopter hovering 200m above the ground. The acceleration due to gravity is 10 m/s2. Calculate the speed at which the cylinder will hit the ground.

2. A ball is thrown vertically upwards at 25 m/s. Gravity caused the ball to decelerate at 10 m/s2. Calculate the maximum height reached by the ball.

Worksheet – using v2=u2+2as



Note: These questions are difficult. Take your time and work methodically.

1. A car begins at a speed of 3m/s and accelerates at 2m/s2 over a distance of 40m, calculate the final speed of the car.

…………………..

2. A person begins moving after initially being stationary, the person accelerates at 0.5m/s2 over a distance of 9m, what is their final speed?

…………………..

3. A car starts from rest and accelerates at 2.5 m/s2 during which it covers a distance of 300 m. What is the final speed of the car?

…………………..

4. A train accelerates at 0.25 m/s2 It starts at 3 m/s and ends up at 7 m/s. How far does it travel during this time?

…………………..

5. A person who is initially stationary is eventually walking at a speed of 1.5m/s after an acceleration of 0.5 m/s2, calculate the distance it takes them to reach this speed.

…………………..

6. A car reaches a speed of 15m/s after an acceleration of 2m/s2 over a distance of 44m, calculate the initial speed.


…………………..

7. A motorbike reaches a speed of 20m/s over 60m, whilst accelerating at 3m/s2, determine the bike’s initial speed.

…………………..

8. A child travels down a slide, at the top the child is initially at rest, at the bottom the child is travelling at a speed of 3m/s, the child’s acceleration is 1m/s2, how long is the slide?

…………………..9. A lorry pulls forward after initially being stationary, it takes the lorry 40m to reach a

speed of 8m/s, calculate the lorry’s acceleration.

…………………..10. A cyclist rides in a 1km downhill race. He passes the start line at a speed of 8 m/s

accelerates constantly at 0.8 m/s2 during the race. What speed does he cross the finish line?

…………………..11. An aeroplane starts from rest and accelerates to take off speed, which is 70 m/s. The

length of the runway is 2km and the ‘plane uses 80% of the runway’. What is the acceleration of the ‘plane?

…………………..

5: Graphs of Motion


Knowledge and Understanding CheckCan you answer the following questions using your knowledge from the previous lessons on this topic?

1. A resultant force of 600N acts on an object with a mass of 3kg. What acceleration will this cause?

……………………….[3]

2. An object accelerates from rest (0m/s) to 25m/s in 8s. What is the acceleration of this object?

……………………….[3]

3. How long will it take a car to come to a stop if it has an initial speed of 30m/s and has a deceleration of 6m/s2?

……………………….[3]

4. A car begins at a speed of 5m/s and accelerates at 5m/s2 over a distance of 45m, calculate the final speed of the car.

……………………….[4]

[Score /13

Learning Outcomes:


1. Identify the difference between a distance-time graph and a velocity-time graph.2. Describe how speed can be found from a distance-time graph.3. Explain how acceleration and distance travelled can be determined from a

velocity-time graph.

Motion Graphs

Distance -Time Graph Velocity-Time Graph


Key Ideas

1. In a distance-time graph, distance is plotted on the y-axis and time is plotted on the x-axis

2. The gradient on a distance-time graph tells us the objects speed.

3. The gradient is calculated by the following:

gradient= change∈ ychange∈x

4. A horizontal line represents a stationary object.

Key Ideas

1. In a velocity-time graph, velocity is plotted on the y-axis and time is plotted on the x-axis

2. The gradient on a velocity-time graph tells us the objects acceleration.

3. The area under a velocity-time graph tells us the distance travelled by the object

4. A horizontal line represents a constant speed.

Worked Examples – Motion Graphs

A. How fast is the object going from:1. AB?

2. BC?

3. CD?

B. 1. How fast is the object going in the first 2 seconds?

2. How far did the object travel in the first 10 seconds?

C. Below is a distance-time graph. Can you sketch the associated velocity time graph for the journey?


5

10

15

Worksheet – Distance-time graphs

1. The distance-time graph shows the journey of a train between two stations.The stations are 6 kilometres apart.

6

5

4

3

2

1

00 1 2 3 4 5 6 7 8 9 10

Tim e (m inu tes )

D is tan ce(k ilo m etre s)

(a) During the journey the train stopped at a signal. For how long was the train stopped?

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

Answer ................................................... minutes(1)

(b) What was the average speed of the train for the whole journey? Give your answer in kilometres per hour.

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

Answer .............................. kilometres per hour(2)

2. Match each description to one of the graphs below. (4)a. A child runs at a constant speed for 40 s before stopping.b. A panda moves slowly at a constant speed for 40 s before stopping.c. A cheetah stalks his prey, moving slowly, stopping occasionally.d. A rabbit runs away from a farmer, not stopping for anything!


3. Draw a distance time graph for an otter that swims 100 m in 30 s, before he gets lazy and drifts along 50 m in 20 s. The otter then relaxes on the riverbank for 10 s. (5)

4. Wayne cycles from Newcastle to Ashington, a distance of 20 miles.The diagram shows the distance-time graph of his journey.

2 0

1 6

1 2

8

4

01 0 .0 0 11 .0 0 1 2 .0 0 1 3 .0 0 1 4 .0 0 T im e

D is tan cefro mN e w ca stle(m iles )

(a) How far from Newcastle is Wayne at 11.00?

Answer .......................................... miles(1)

(b) What is Wayne’s average speed over the first 2 hours of his journey?

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

Answer ........................................... mph(2)

(e) Darren travels from Ashington to Newcastle by bus.He leaves Ashington at 10.00 and arrives in Newcastle at 11.00On the diagram draw a possible distance-time graph of Darren’s journey.

(1)


Worksheet – Velocity-time graphs

A. The following table represents the movement of a car:-

Velocity (m/s) 0 5 10 15 15 15 12 9 6 3 0

Time (s) 0 1 2 3 4 5 6 7 8 9 10

Draw a Velocity time graph (with time on the x-axis)

Use your graph to answer the following questions:

1. What is the acceleration of the car between 0 and 3 seconds?[Remember acceleration is equal to the change in velocity ÷ time]…………………………………………………………………………………………………………………………………………………………………………………………

2. Between 3 and 5 seconds the car is still accelerating – true or false? Explain your answer.…………………………………………………………………………………………………………………………………………………………………………………………

3. How would you describe the movement of the car between 5 and 10 seconds? …………………………………………………………………………………………………………………………………………………………………………………………

4. What distance does the car travel in the first 3 seconds?…………………………………………………………………………………………………………………………………………………………………………………………

5. What distance does the car travel in the total journey?…………………………………………………………………………………………………………………………………………………………………………………………


B. A racing car (at rest) accelerates uniformly from the starting grid on the race track and reaches a top velocity of 30 meters/second after 5 seconds. For the next 4 seconds the acceleration is 0 and finally the car decelerates (brakes) at 4meters/second/second for 5 seconds.

Draw a Velocity time graph (with time on the x-axis). If you are stuck, try marking what the velocity would be after each second!

Use your graph to answer the following questions:

1. What distance does the car travel in the first 5 seconds?

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

2. What is the velocity of the car after 7 seconds?

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

3. What is the velocity of the car after 14 seconds?

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

4. If the car carried on decelerating at 4m/s2, how many more seconds would it take before it came to a stop?

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

5. What is the acceleration in the first 5 seconds?

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


Stretch Activity – Resultant Force in 2D

Forces do not always act along one line. Sometimes the Resultant force ends up at an angle. Watch the following video and make notes below on how to use a scale drawing to add vectors in 2D.

https://www.youtube.com/watch?v=JRsFx69UdDc

Worksheet – Vectors in 2D

Use what you have learnt to find the resultant force in the following examples.

1. What is the resultant force of 50N acting north and 25 N acting east? (give a bearing to represent the final direction of the resultant force).

2. What is the resultant force of 300N acting north and 400 N acting east? (give a bearing to represent the final direction of the resultant force).


https://www.youtube.com/watch?v=JRsFx69UdDc

3. What is the resultant force of 60N acting south and 60 N acting east? (give a bearing to represent the final direction of the resultant force).


Challenging Forces

Past Paper Questions

Q1. A train travels 9 km from station A to station B.

It takes 15 minutes.

(a) (i) State the equation linking average speed, distance moved and time taken.

(1)

(ii) Calculate the average speed of the train and give its unit.

(3)

Average speed = ........................................ unit ..................................


(iii) The maximum speed of the train must be higher than the value you havecalculated.

Explain why.

(2)

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

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

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

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

(b) The train continues along a straight track from station B to station C.

The graph shows how the velocity of the train changes with time during this part ofthe journey.

(i) Use the graph to calculate the acceleration of the train, in m/s2, during the first100 seconds after it leaves station B.

(3)

Acceleration = ........................................................... m/s2

(ii) Use the graph to calculate the distance, in m, between station B and station C.


(3)

Distance = ........................................................... m

(Total for question = 12 marks)


Q2.

The graph shows how the velocity of an aircraft changes as it accelerates along a runway.

(a) Use the graph to find the average acceleration of the aircraft.

(3)

Acceleration = ........................................................... m/s2


(b) Explain why the acceleration is not constant, even though the engines produce aconstant force.

(3)

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

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

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

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

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

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

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



Q3.

The diagram shows the driving force on a sports car as it moves along a race track.

(a) Name two forces that oppose the driving force.

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

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

(b) The car has a mass of 1400 kg.

The acceleration of the car is 5.5 m/s2.

(i) State the equation linking force, mass and acceleration.

(1)

(ii) Calculate the force causing this acceleration.

(2)

Force = ........................................................... N


(c) Graph 1 shows how the velocity of the car changes with time.

Calculate the distance that the car travels in the first four seconds.

(3)

Distance = ........................................................... m


(d) As the car travels further along the track, its acceleration changes as shown in graph 2.

(i) Which feature of graph 2 shows that the acceleration changes?

(1)

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


(ii) The acceleration changes even though the driving force does not change.

Suggest two possible reasons for this change in acceleration.

(2)

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

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

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

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



Q4.

Two students, Jenny and Cho, are investigating motion.

Jenny walks in a straight line.

Cho measures the distance Jenny has walked at 10 s intervals.

(a) State two measuring instruments the students should use.

(2)

1 ................................................................................................................................................

2 ................................................................................................................................................

(b) The table shows their measurements.

Draw a graph of distance against time for this data.

(3)


(c) How far had Jenny walked after 35 s?

(1)

Distance walked = ........................................................... m

(d) (i) Describe how Jenny's speed changed during the investigation.

(1)

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(ii) What feature of the graph shows this change?

(1)

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Q5.

(a) Parachutes are used to slow down a spacecraft as it falls through the atmosphere.

Photograph G shows an Apollo spacecraft with three parachutes attached.

This spacecraft falls at a constant velocity.

(i) State the name of this constant velocity.

(1)

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(ii) Explain why this velocity stays at a constant value.

(3)

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(iii) Photograph H shows an identical Apollo spacecraft. Only two of its parachutesare working.

Explain how the constant velocity reached by this spacecraft compares withthe constant velocity of the spacecraft shown in photograph G.

(2)

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(b) Photograph I shows a Space Shuttle using a parachute when it lands on a runway.

Explain what would happen to the stopping distance of the Shuttle if this parachutedid not open.

(2)

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Challenging Forces

Spec Point Notes

Challenging Forces Specification Notes

1.01 use the following units: kilogram (kg), metre (m), metre/second (m/s), metre/second2 (m/s2), newton (N), second (s) and newton/kilogram (N/kg)

1.03 plot and explain distance−time graphs


1.06 know and use the relationship between acceleration, change in velocity and time taken:acceleration = change in velocity/time taken

a= v−ut

1.07 plot and explain velocity-time graphs

1.08 determine acceleration from the gradient of a velocity−time graph

1.09 determine the distance travelled from the area between a velocity−time graph and the time axis


1.10 use the relationship between final speed, initial speed, acceleration and distance moved:

(final speed)2 = (initial speed)2 + (2 × acceleration × distance moved)

v2=u2+2as

1.11 describe the effects of forces between bodies such as changes in speed, shape or direction


1.12 identify different types of force such as gravitational or electrostatic

Gravitational, weight, friction, electrostatic, air resistance (drag), tension (force in a spring), upthrust, lift, thurst

1.13 understand how vector quantities differ from scalar quantities

Scalars are quantities that only have magnitude (size) Vectors are quantities that have magnitude (size) and direction

1.14 understand that force is a vector quantity

1.15 calculate the resultant force of forces that act along a line

1.17 know and use the relationship between unbalanced force, mass and acceleration:

force = mass × acceleration

F = m × a


1.21 describe the forces acting on falling objects (and explain why falling objects reach a

terminal velocity)

1.22 practical: investigate how extension varies with applied force for helical springs, metal wires and rubber bands


1.23 know that the initial linear region of a force-extension graph is associated with Hooke’s law

1.24 describe elastic behaviour as the ability of a material to recover its original shape after the forces causing deformation have been removed


[m]

[N]


thequarkyteacher.files.wordpress.com€¦ · Web view1.23know that the initial linear region of a force-extension graph is associated with Hooke’s law. 1.24describe elastic behaviour

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