1. Lesson: Forces

2. A force is a _____ or ____. Push Pull
which can change the shape, speed or direction of an object.
Can you think of some examples of forces changing the:
(i) shape, (ii) speed and (iii) direction of an object?

3. A force is measured in Newtons (N).
A shopping trolley is pushed with a force of:
~ 75 N.
SIR ISAAC NEWTON

4. There are many different forces.
Can you give some examples?

5. Spring Balance We can measure small forces using a:
Hang an object on the hook and read the scale to find the force of the object pulling down.

6. Forces act in pairs.
For every force there is an equal and opposite force.

7. FRICTION is a force. It slows down movement between
two objects in contact.
How can we prevent friction?

8. Friction is a disadvantage if we want to go quickly.
Friction is an advantage if we want to go slowly.

9. Why is it important that tyres have good treads?

10. Describe what is in this picture.
What do you think happened to the damaged tyres?

11. Friction causes heat. 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?

12. We can reduce friction using a Lubricant.
Where do we use oil to reduce friction?
OIL

13. 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.

14. What are the forces in this picture?

15. Review Questions 1. Forces are measured using a ___________.
HINT
2. What unit are forces measured in?
HINT

16. Question to think about!
Why doesn’t the satellite fall to earth?