1. FRICTIONAL
FORCE

2. A force that opposes motion

4. What is friction?

6. When does friction occur?
Friction occurs when two surfaces are in contact

7. Also…
When a liquid or gas is pushed out of the way of a moving object

8. Why does friction occur?
When the grooves and ridges of a surface are in contact with the grooves and ridges of another surface, this produce friction. ie the interlocking between the two surfaces causes friction.

10. Friction depends on…/What increases friction?
Roughness of Surfaces
Weight of Objects

11. What does the amount of friction depend on?
The amount of friction depends on how well the surfaces grip each other. Tyres on a road have very high friction (they don't slip), Skates on ice have very low friction (they slip easily).

12. In a liquid or a gas
For a solid object moving through a liquid or gas,the amount of friction depends on the shape and surface area of the objectand the viscosity (thickness ) of the liquid.
The frictional force that fluids exerts on an object is called drag.

14. TYPES OF FRICTION
KINETIC AND
STATIC

15. What is kinetic friction?
Is the friction between two moving surfaces

16. Sliding and Rolling

17. Static friction
Static friction is the friction that exists between a stationary object and the surface on which it's resting.

18. Static friction

19. Is friction good or bad?
Friction can be good. When we walk we push backwards against the ground,the opposing force pushes us forwards. Without friction our feet would slip and walking would be impossible.

20. To stop your bicycle (brake system)
It is also good
To stop your bicycle (brake system)

21. Friction leads to wastage of energy. Friction leads to wear and tear.
But sometimes is bad…
Friction leads to wastage of energy.
Friction leads to wear and tear.

22. Some ways to reduce friction

23. Some ways to increase friction

24. THANK YOU