1 / 19

Chapter 6

Chapter 6. Momentum. This chapter is concerned with inertia and motion. Momentum helps us understand collisions. Momentum and Collisions. Momentum. Momentum = mass X velocity p = mv Momemtum is a vector. Sample Questions.

camden
Télécharger la présentation

Chapter 6

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 6 Momentum

  2. This chapter is concerned with inertia and motion. Momentum helps us understand collisions. Momentum and Collisions

  3. Momentum • Momentum = mass X velocity • p = mv • Momemtum is a vector

  4. Sample Questions • Which has more momentum, a 1-ton car moving at 100 km/hr or a 2-ton truck moving at 50 km/hr? • Car p = mv = (1 ton)(100km/hr) • Truck p = (2 ton)(50 km/hr)

  5. Large Momentum Examples: • Huge ship moving at a small velocity • High velocity bullet P = mv P = mv

  6. Impulse • Newton’s Second Law can read SF = ma = m(Dv/Dt) = (Dmv)/(Dt) = (Dp/ Dt) Rearranging, Impulse = Dp = FDt

  7. Sample Question • Does a moving object have impulse? Impulse is not a property of the object, but something that it can give or get from an interaction. Notice that it is not motion that gives us an impulse (v) but a change in motion (Dv).

  8. Sample Question • Does a moving object have momentum? Yes, but recall that motion is relative, so the momentum depends on having velocity with respect to the standard of rest.

  9. When Force is Limited • Apply a force for a long time. • Examples: • Follow through on a golf swing. • Pushing a car. FDt

  10. Make it Bounce p1 p2 = -p1 Dp = p2 - p1 = -p1 - p1 = -2p1

  11. Minimize the Force • To minimize force … • Increase Dt • catching a ball • Bungee jumping FDt

  12. Apply a force for a short time. Examples: Boxing Karate Maximize Momentum Change FDt

  13. Conservation of Momentum • If SF = 0, then impulse = Dp = zero, or Momentum is conserved

  14. Demonstrations • Rocket balloon • Cannon • Rocket Scooter

  15. When can Momentum be Conserved? • Internal forces cannot cause a change in momentum of the system. • For conservation of momentum, the external forces must be zero.

  16. COLLISIONS • Collisions involve forces internal to colliding bodies. • Inelastic collisions - conserve momentum • Totally inelastic collisions - conserve momentum and objects stick together • Elastic collisions - conserve energy and momentum

  17. M M M M Inelastic Collisions v = 10 v = 0 Before Collision p = Mv v’ = 5 v’ After Collision p = 2Mv’ Mv = 2Mv’ v’ = ½ v

  18. Collisions Air Track Link

  19. Elastic Collisions Conserve Energy and Momentum Before Collision Equal masses Case 1: Case 2: M > M Case 3: M < M

More Related