1. Circular Motion

2. Introduction What is Newton’s First Law how does it relate to circular motion? How does Newton’s second law relate to circular motion?

3. Acceleration ViVi VfVf ViVi VfVf

4. ViVi VfVf VfVf

5. Acceleration

6. Exam Question (VCAA 2010) A racing car of mass 700 kg (including the driver) is travelling around a corner at a constant speed. The car’s path forms part of a circle of radius 50 m, and the track is horizontal. The magnitude of the central force provided by friction between the tyres and the ground is 11 200 N. Question 1 What is the speed of the car? (2 marks) Question 2 What is the acceleration of the car as it goes around the corner? (2 marks)

7. Exam Question (VCAA, 2009) Question 3 Draw an arrow to show the direction of the net force on the motorcycle.

8. On the diagram, draw the forces acting on the car. Remember the car is travelling in a circular path. Centre of circular path

9. On the diagram, draw the forces acting on the car. Remember the car is travelling in a circular path. Centre of circular path FgFg FNFN FNFN FfFf FfFf

10. On the diagram, draw the forces acting on the car. Remember the car is travelling in a circular path. Centre of circular path FgFg FNFN FNFN FfFf FfFf Since the vertical forces are balanced, the net force (which we call centripetal force) is the sum of the sideways frictional forces.

11. Ball on a string

12. FgFg

13. FgFg FtFt

14. FgFg FtFt FgFg FtFt

15. FgFg FtFt FgFg FtFt

16. FgFg FtFt FgFg FtFt

17. Example: Ball on a string A ball of mass 250 g is attached to string in a game of totem tennis. The string makes an angle of 40 o to the vertical pole. Calculate: a. the net force on the ball b. the tension in the string c. the length of the string in terms of it’s speed, v?

18. Banked Corners

19. FgFg

20. FgFg FNFN

21. FgFg FNFN FNFN FgFg

22. FgFg FNFN FNFN FgFg

23. FgFg FNFN FNFN FgFg

24. FgFg FNFN FNFN FgFg

25. FgFg FNFN FNFN FgFg

26. Exam Question: VCAA 2010 Question 4 On the diagram, draw an arrow to indicate the direction of the acceleration of the rider (1mark)

27. Exam Question: VCAA 2010 Question 5 The circular path of the bicycle has a constant radius of 120 m, and the bicycle will be travelling at a constant 9 m s -1. What should be the value of the angle of the bank, θ, so that the bicycle travels around the corner with no sideways frictional force between the tyres and the track? (3 marks)

28. Banked Corners FgFg FNFN FNFN FgFg The force diagram doesn’t consider friction. Challenge: What would the force diagram look like if we considered friction? In which direction would the net force be?

29. Leaning into corners

30. FgFg FNFN FfFf