Lesson: Forces

Science Differentiation in action

A force is a _____ or ____.

which can change the shape, speed or direction of an object.

Push Pull

Can you think of some examples of forces changing the: (i) shape, (ii) speed and (iii) direction of an object?

Science Differentiation in action

A shopping trolley is pushed with a force of:

A force is measured in Newtons (N).

SIR ISAAC NEWTON

~ 75 N.

Science Differentiation in action

There are many different forces.

Can you give some examples?

Science Differentiation in action

We can measure small forces using a:

Spring Balance

Hang an object on the hook and read the scale to find the force of the object pulling down.

Science Differentiation in action

Forces act in pairs.

For every force there is an equal and opposite force.

Science Differentiation in action

FRICTION is a force.It slows down movement betweentwo objects in contact.

How can we prevent friction?

Science Differentiation in action

Friction is a disadvantage if we want to go quickly.

Friction is an advantage if we want to go slowly.

Science Differentiation in action

Why is it important that tyres have good treads?

Science Differentiation in action

Describe what is in this picture.

What do you think happened to the damaged tyres?

Science Differentiation in action

Rub your hands together very quickly.

What happens?

Friction causes heat.

Now put some washing up liquid on your hands and rub them together again.

What happens?

Science Differentiation in action

We can reduce friction using a Lubricant.

Where do we use oil to reduce friction?

OIL

Science Differentiation in action

An apple falls to earth because the force of gravity acts between the apple and the earth.

Gravity is the FORCE of attraction between two objects that have mass.

Science Differentiation in action

What are the forces in this picture?

Science Differentiation in action

1. Forces are measured using a ___________.

Review Questions

2. What unit are forces measured in?

HINT

HINT

Science Differentiation in action

Why doesn’t the satellite fall to earth?

Question to think about!