Here's the Problem: A bullet of mass m=19.8 g is shot vertically upward into a block of wood of mass M=119 g that is initially at rest on a thin sheet of paper. The bullet passes through the block, which rises to a height of H=0.71m above its initial position before falling back down. The bullet continues upward to a maximum height of h=4.70m. Using energy conservation, you can express the velocities of the bullet and block immediately after the bullet exits the block in terms of the heights h and H. Use this to somehow determine the initial velocity of the bullet.(adsbygoogle = window.adsbygoogle || []).push({});

This is How I Tackled Throught the Guidance of BOTH My (HORRIBLE) Physics Book and My (EVEN WORSE) T.A.:

Using Conservation of Energy I came up with the Eq'n:

(1/2)(m+M)v^2= MgH + mgh

I solved for v and got 5.01

Apparently that's not the answer, so then I took a hint given in the book and Used Conservation of Momentum to get the equation:

mv(initial) = (M + m)v

I solved for v initial and got 35.1 m/s

But apparently, It's STILL Wrong.. I've tried slight variations of the above two equations, and yet, I still continue to get it wrong. I'm not sure what the problem is..Can anyone help?

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# Homework Help: Collision Problem using Conservation of Momentum and Energy

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