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Oct 20, 2008

Homework Problem 3/269


Suggestions:
Draw FBD's of A alone, B alone and A+B together. From these FBD's:
  1. From A alone, you know that momentum of A is conserved in the y-direction.
  2. From B alone, you know that momentum of B is conserved in the y-direction.
  3. From A+B together, you know that momentum of A+B is conserved in the x-direction.
These give you three equations. The fourth equation is the coefficient of restitution equation relating the differences in the x-components of velocity for A and B.

Let us know if you have any questions on this.
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2 comments:

garrettmocas said...

I used the e equation and the other, longer equation and solved them both for Va2x and then set them equal and could not get the correct solution. Any ideas?

October 22, 2008 at 8:37 AM
Lindsey VanDeMark said...

that sounds like it should work. The e equation should be .75=(Vb'-Va')/(Va-Vb) all in the x direction so you have to remember Vbx is a negative. The other equation should be Va+Vb=Va'+Vb' because the masses are all the same and therefore cancel out. solve these simultaneously and they should come out correct. Don't forget to find the magnitude using your x and y component. These equations only give you the x component.

This is what I did, hope it helps.

October 22, 2008 at 10:26 AM

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