RE: PHYSICS

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A man (weighing 915 N) stands on a long railroad flatcar (weighing 2805 N) as it rolls at 18.0 m/s in the positive direction of an x axis, with negligible friction. Then the man runs along the flatcar in the negative x direction at 40.00 m/s relative to the flatcar. What is the resulting increase in the speed of the flatcar?

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* Physics - bobpursley, Sunday, February 25, 2007 at 5:25pm

Use conservation of momentum. I will be happy to critique your thinking.

* Re: Physics - COFFEE, Sunday, February 25, 2007 at 11:19pm

Ok, so I use mv = m1v1 + m2v2??? And I would get m1 and m2 by dividing the weights by 9.8 m/s^2? Please explain.

The original momentum is..
(915+2805)g18
That is equal to the final momentum
915g*(-40+18) + 2805g(V+18)
solve for V.

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