College and Engineering Physics Elastic and Inelastic Collisions

College and Engineering Physics Elastic and Inelastic Collisions TOC Conservation Collisions 1

College and Engineering Physics Elastic and Inelastic Collisions Conservation of Linear Momentum TOC 2 The change in momentum of a system is equal to the impulse put on the system.

College and Engineering Physics Elastic and Inelastic Collisions Conservation of Linear Momentum TOC For example: Jeff Bagwell hits a baseball… Initially 3

College and Engineering Physics Elastic and Inelastic Collisions Conservation of Linear Momentum TOC For example: Jeff Bagwell hits a baseball… During hit 4

College and Engineering Physics Elastic and Inelastic Collisions Conservation of Linear Momentum TOC For example: Jeff Bagwell hits a baseball… Finally 5

College and Engineering Physics Elastic and Inelastic Collisions Two types of collisions TOC Elastic: The objects do not stick together or change shape. Momentum and kinetic energy are conserved. Inelastic: The objects do stick together and/or change shape. Only momentum is conserved! 6

College and Engineering Physics Elastic and Inelastic Collisions Example of an elastic collision TOC The cue ball hits two billiard balls initially at rest on a billiard table. Assume that the cue ball stops after hitting the other balls. What is the final velocity of the red and blue ball? y θ x 7

College and Engineering Physics Elastic and Inelastic Collisions TOC y θ x 8

College and Engineering Physics Elastic and Inelastic Collisions TOC y θ x 9

College and Engineering Physics Elastic and Inelastic Collisions TOC y θ x 10 We have three equations and four unknowns. We cannot solve this problem without more information. You will usually be given the speed or angle of one of the balls.

College and Engineering Physics Elastic and Inelastic Collisions Example of an inelastic collision TOC 11 A pieces of putty is thrown against a box sitting at rest on a frictionless table. If the putty is twice the mass of the box, what is the speed of the box/putty combination compared to the original speed of the putty?

College and Engineering Physics Elastic and Inelastic Collisions Impulse and Momentum TOC x-component Momentum Impulse 12 The total impulse acting on a systems is ALWAYS equal to the change in its momentum

College and Engineering Physics Elastic and Inelastic Collisions Impulse and Momentum TOC 13 Elastic Collisions Object 1 Object 2 p 0 x 2 kg m/s 1 kg m/s pfx -3 kg m/s p 0 y During collisions momentum is always conserved and kinetic energy is sometimes conserved Inelastic Collisions Object 1 Object 2 p 0 x 1 kg m/s 6 kg m/s pfx -3 kg m/s 5 kg m/s 0 kg m/s p 0 y 2 kg m/s 0 kg m/s pfy 2 kg m/s -2 kg m/s pfy 3 kg m/s -1 kg m/s K 0 12 J 6 J Kf 8 J 10 J

College and Engineering Physics Elastic and Inelastic Collisions TOC This is the last slide. Click the back button on your browser to return to the Ebook. 14