1. Why doesn’t gravity make you fall though the floor?
How does a car seat belt protect you in a car accident?
Why is it so difficult to walk on ice?
Why do Olympic swimmers & cyclist's shave their legs?

3. What are forces?
Forces are a push or a pull.
Are measured in Newtons

4. When you fly a kite, do you use a push force or a pull force?

5. Which of the following people are using a push force?
(b)
(d)
(c)

6. What are forces? Forces can: Change the speed of an object
Change the direction of movement of an object
Change the size or shape of an object

7. Mechanical forces obey three laws called Newton’s Laws of Motion.

8. The first law... …If there is no Net force acting on an object
IT is not moving, (at rest) OR

9. it is moving at a steady speed in a straight line…
or …..
it is moving at a steady speed in a straight line…
Ie the object speed does not change!

10. So to start something moving ...

11. …or speed it up, slow it down or stop it ...

12. …or change its direction...

13. A force must be applied!

14. The second law states F = ma
An unbalanced force applied to an object will change its speed in the same direction as the force.
A change in speed is called acceleration and the amount of acceleration depends on the strength of the force.
F = ma

15. A big force will give a bigger acceleration than...

16. … a small force applied to the same mass.

17. kinds of Forces Contact forces: Non-contact forces Thrust Friction
Support force (reaction force)
Tension / Compression
Torque
Non-contact forces
Gravity and Weight force
Magnetic
Electrostatic
Nuclear

18. Name the force indicated by the arrow.

19. Name the force indicated by the arrow.

20. Name the force indicated by the arrow.

21. Name the force indicated by the arrow.