- #1
seanmcgowan
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Homework Statement
A bullet with a mass of 6.00 g is fired through a 1.25 kg block of wood on a frictionless surface. The initial speed of the bullet is 896m/s, and the speed of the bullet after it exists the block is 435 m/s. At what speed does the block move after the bullet passes through it?
Homework Equations
I think I have the corect momentum, but the answer for the acceleration of the block seems a bit too easy. Is it right, or am I way off?
The Attempt at a Solution
First I drew a free body digram. The diagram has the bullet on the left, with its velocity and mass (Mass=.006 Kg Velocity=896 m/s), and the stationary block of wood with its mass and velocity (Mass=1.25 Kg Velocity=0 m/s) .
Since this is a collision problem, I figured I should find the momentum using the formula Mass*Velocity=Momentum. So, for the bullet... .006 Kg * 896m/s= 5.376 Kg*m/s (initial momentum) and... .006 Kg * 435 m/s= 2.610 (final momentum). For the block of wood... 1.25 Kg * 0 m/s= 0 Kg*m/s (Initial momentum) and... 1.25 Kg * 461 m/s (the difference of the bullet's Initial and Final velocities)= 576 Kg * m/s
I realize this is momentum not the block's velocity. I'm not sure what else to do because the only other logical answer is 896-435= 461 m/s and that just seems way to easy for a physics problem. Or am I over thinking this?