Roller Coaster Physics

1. Roller Coaster Physics

2. Dynamics • Why things move • Accelerations caused by Forces

3. Non Contact Contact Gravitational Electromagnetic Nuclear Pushes Pulls Electric Magnetic Normal Friction Tension M T f N W Forces perpendicular to surface

4. Labeling Forces What forces are acting on the yellow ball? F

5. Fby, on Labeling Forces What forces are acting on the yellow ball?

6. Labeling Forces What forces are acting on the yellow ball? Wby, on

7. Labeling Forces What forces are acting on the yellow ball? WEarth, Ball

8. Fby, on Labeling Forces ANYTHING LESS IS AN INCOMPLETE ANSWER!!!

9. 0 Sir Isaac Newton (1642-1727)

10. Newton’s Laws of Motion • 1st Law: • no net force  no acceleration • no acceleration  no change in motion • Objects at rest will remain at rest and objects in motion will remain in motion at constant speed, in a straight line, unless acted on by a net force

11. Newton’s Laws of Motion • 1st Law: • no net force  no acceleration • no acceleration  no change in motion • Objects at rest will remain at rest andobjects in motion will remain in motion at constant speed, in a straight line, unless acted on by a net force

12. Mass • Measure of how much ‘stuff’ • Measure of how hard it is to speed up or slow down the object • Mass and weight are very different

15. POP!

16. F a Fnet a F  a More net force - more acceleration(constant mass)

17. F 1  M a a F a More mass - less acceleration(constant net force)

18.  M Fnet Fnet Fnet  Constant * a a a M  M Putting it all together Newton is defined such that constant = 1. Newton’s 2nd Law

19. Newton’s Laws • 1st • Objects at rest will stay at rest and objects in motion will stay in motion, at a constant speed, in a straight line, unless acted on by a net force. • 2nd • Objects with a non-zero net force accelerate in the direction of the net force via Fnet = ma

20. THE BRICK OF DEATH!!! I Physics

21. What THING is pushing on the rocket? • Is this a contact or non-contact force?

22. Poor Gary: Gary has a major problem. After studying Newton’s Third Law in his physics class, he has convinced himself of its validity. Unfortunately, he has convinced himself while sitting in a closed room with a single door. He reasons to himself: “If I push on the door to go out, Newton’s 3rd Law tells me that the door is going to push back with an equal force. That force is going to cancel the force that I push with. Even if I push as hard as I can, that door is going to push back just as hard! Oh no! I’m stuck in this room! Why did I ever take physics!”

23. The famous bug problem: • A bug splats on the windshield of a car moving at 100 mph. Which feels the greater force, the car or the bug? • Which has the worst day?

24. NFS NSP person scale WES WEP NPS Newton’s 3rd Law and the Scale Apparent Weight True Weight

25. Apparent weight • measured as the reading of the scale • equal to the normal force of the scale on your feet • equal to weight for a=0

26. v = constant Apparent Weight NSP a = 0 WEP True Weight Elevator

27. a is upward Apparent Weight NSP a WEP True Weight Elevator

28. a is downward Apparent Weight NSP a WEP True Weight Elevator

29. a =9.8 m/s/s down NSP g WEP Elevator How large should the normal force be?

30. g Elevator How large should the normal force be? a =9.8 m/s/s down Apparently Weightless?? WEP

31. The weightlessness of space!

32. What’s his mass? 80 kg

33. What’s his weight? 648 N ! What ?

34. Apollo 17 Earth as seen from the Moon

35. What is the correct orbit of the space shuttle?

36. What is the correct orbit of the space shuttle?

38. a = 8.1 m/s2 a = 8.1 m/s2 a = 8.1 m/s2 a = 8.1 m/s2 a = 8.1 m/s2 a = 8.1 m/s2

39. Orbit • “…there is an art to flying, or rather a knack. The knack lies in learning how to throw yourself at the ground and miss.” • Douglas AdamsLife, The Universe, and Everything

41. Circular motion Which direction is the instantaneous velocity?

42. Uniform Circular motion Which direction is the instantaneous velocity? Which direction is the acceleration?

43. Uniform Circular motion Which direction is the instantaneous velocity? Which direction is the acceleration? TS,B Freebody WE,B

44. WE,B Uniform Circular motion Which direction is the instantaneous velocity? Which direction is the acceleration? TS,B Freebody

45. Ty Tx WE,B Uniform Circular motion Which direction is the instantaneous velocity? Which direction is the acceleration? Freebody Aren’t we missing something?

46. Ty Tx WE,B THE CENTRIFUGAL FORCE! • Centrifugal. adj. Moving or directed away from the center.

47. CENSORED CENSORED Ty Tx WE,B THE CENTRIFUGAL FORCE! • Centrifugal. adj. Moving or directed away from the center.

48. Non Contact Contact Gravitational Electromagnetic Nuclear Pushes Pulls Electric Magnetic Normal Friction Tension M T f N W Forces perpendicular to surface

49. CENSORED CENSORED CENSORED Ty Tx WE,B THE CENTRIFUGAL FORCE! • Centrifugal. adj. Moving or directed away from the center. • The centri*&%#l force DOES NOT EXIST! • For uniform circular motion the net force must be towards the center of the circle. • Therefore: The acceleration is ‘center seeking’

50. CENSORED CENSORED CENSORED Ty Tx WE,B THE CENTRIFUGAL FORCE! • Centrifugal. adj. Moving or directed away from the center. • The centri*&%#l force DOES NOT EXIST! • For uniform circular motion the net force must be towards the center of the circle. • Therefore: The acceleration is centripetal