FORCES IN ACTION

FORCES IN ACTION

MACHINES MOVE THE WORLD

UNIT 2

Marta Vidal VidalL3 L4 L5 L6

ISAAC NEWTON (1642-1727)FIRST LAW OF MOTION. INERTIAAn object at rest stays at rest,

an object in motion stays in motion.Why does an object stop its

motion?Why do objects change its

direction?Because it is the result of an UNBALANCED FORCE

applied upon an object.

Unbalanced force

Start motionStop motionChange directionChange shape

Balanced force

• No change• No visible effect

WHICH FORCES INFLUENCE MOTION?

Contact forces Friction

Push/Pull Weight

Non-contact forcesGravityMagnetism superconducting

FORCE is any influence that causes a free body to undergo a change in speed, a change in direction, or a

change in shape.

HANDS ON! FrictionPROBLEM:

How do different surfaces affect the movement of the objects? MATERIALS: Pencil, toy car, metric tape, 4 clothespegs, tape, scissors, aluminium foil, wax paper, recycled paper, sand paper, a calculator and plastic cable covers. STEPS:

1. Predict the distance of the toy car on each surface.2. Create a ramp using 4 clothespegs and plastic cable covers.3. Drop the toy car and measure the distance.4. Do 3 different trials for each surface and calculate total distance.

Play with friction

HANDS ON! FrictionPROBLEM:

How do different surfaces affect the movement of the objects?

STEPS:

1. Predict the distance of the toy car on each surface.

SURFACEPREDICTION

cmTRIAL 1

cmTRIAL 2

cmTRIAL 3

cm

DISTANCET1+T2+T3

3Aluminium

foil        cm

Wax paper         cm

Recycled paper

        cm

Sand paper         cm

HANDS ON! FrictionPROBLEM:

How do different surfaces affect the movement of the objects? 

STEPS:

2. Create a ramp using 4 clothespegs and plastic cable covers.

HANDS ON! FrictionPROBLEM:

How do different surfaces affect the movement of the objects? 

STEPS:

3. Drop the toy car and measure the distance.

4. Do 3 different trials for each surface and calculate the total distance.

  SURFACE

PREDICTIONcm

TRIAL 1cm

TRIAL 2cm

TRIAL 3cm

DISTANCET1+T2+T3

3Aluminium

foil        cm

Wax paper         cm

Recycled paper

        cm

Sand paper         cm

Total distance = trial 1 + trial 2 + trial 3 3

WEIGHTMASS is a measurement of how much matter is in an object.WEIGHT is a measurement of how hard gravity is pulling on that object.

On Earth 1 kg of mass = 9.8 newtonsGravity on Earth is 1G = 9.8 newtons

WEIGHT = MASS x GRAVITYWEIGHT = 1kg x 1 1

WEIGHT = 1 Kg or is = 9.8 newtons

On Earth our mass is equal to our weight.MASS = 1kg WEIGHT= 1kg

ENGLISH DECIMALS IS IN . (DOT)SPANISH DECIMALS IS IN , (COMMA)

Our MASS is the same everywhere but if we travel over the universe we have a

different WEIGHTMASS = 60 Kg

WEIGHT = 60 Kg

MASS = 60 KgWEIGHT = 60 x 0.16

WEIGHT = 9.6 Kg

What will happen to our weight if we travel around space?

Calculate your weight in the Solar SystemLook at the gravity of the planets, the sun and the Moon and calculate your weight in respect to those.

Is it your weight different or is it equal?

My weight never changes.changes.

 Is it your mass different or is it equal?

My mass never changes.changes.

Look at your results and underline the correct part of the sentence.

On Earth On the moonWeight = mass x gravity in newtons

WEIGHT = ………. x 9,8 WEIGHT = ………. x 1,5

WEIGHT = ….....newtons WEIGHT = ….....newtons

Calculate your weight in newtons

WHAT IS FORCE?It can be a PUSH or a PULL.

PUSH PULLFORCE FORCE

OBJECT

Is it a push or a pull?

ISAAC NEWTON (1642-1727) SECOND LAW OF MOTION.

The strength of a force is equal to the amount of the mass involved multiplied by any acceleration applied to it.

F = m x aIf the mass is bigger the effect of the FORCE is smaller

If the mass is smaller the effect of the FORCE is bigger

THE UNIT FOR THE FORCE IS IN NEWTONS

F

F

HANDS ON! Newtons

Objects PREDICTION MASSFORCE

NEWTONSResult

PROBLEM: How do you use a dynamometer?What is the relationship between mass and force?

MATERIALS:- Pencil- Tape measure- Weighing scale- Dynamometer- 3 objects.

STEPS: 1. Predict the power of the force needed to move the objects. Write a number from 1 to 3 (from bigger force to a smaller force).

HANDS ON! Newtons

Objects PREDICTION MASSFORCE

NEWTONSResult

PROBLEM: How do you use a dynamometer?What is the relationship between mass and force?

MATERIALS:- Pencil- Tape measure- Weighing scale- Dynamometer- 3 objects.

STEPS: 2. Measure the objects with a weighing scale and record it in your data table.

HANDS ON! Newtons

Objects PREDICTION MASSFORCE

NEWTONSResult

PROBLEM: How do you use a dynamometer/spring scale?What is the relationship between mass and force?

MATERIALS:- Pencil- Tape measure- Weighing scale- Dynamometer- 3 objects.

STEPS: 3. Put a tape measure on the floor and measure 100 cm in straight line.4. Attach the object to the dynamometer and pull it along a distance of 100 cm and record the result in your data table.

HANDS ON! NewtonsPROBLEM: How do you use a dynamometer?What is the relationship between mass and force?

MATERIALS:- Pencil- Tape measure- Weighing scale- Dynamometer- 3 objects.

STEPS: 5. Write your conclusion about the experiment.6. Share and check the results with the whole class.

Write your CONCLUSIONS

If the mass of an object is biggersmaller

the force needed to move it is bigger

smaller.

If the mass of an object is bigger the force needed to move it is

bigger. If the mass of an object is smaller the force needed to move it is smaller.

ISAAC NEWTON (1642-1727)

THIRD LAW OF MOTION ACTION AND REACTION

All forces occur in pairs.

For every action that takes place there is an equal and opposite reaction.

GRAVITY

NON-CONTACT

FORCES

CONTACT FORCES

PULL

PUSH

FORCE

FRICTION

MAGNETISMForce of attraction or repulsion acting between ferromagnetic materials like iron.

It is a force that pulls all objects towards the center of the Earth.

It is the force resisting the relative motion of solid surfaces, fluid layers, and/or material elements sliding against each other.

It is any influence that causes a free body to undergo a change in speed, a change in direction, or a change in shape.

It is a force that can move something away from somebody/something.

It is a force that can move something towards somebody/something.

It is a force applied to an object by another body that is not in direct contact with it.

It is a force that acts at the point of contact between two objects.