Conservation of Energy & Momentum Question!!!!!!!!?

Question

A 110 g ball is thrown horizontally at a 1011g box with a hole in it. The coefficient of friction between the box and the surface it is on is 0.24. When the ball enters the box, it does not bounce out and the whole unit moves 17cm. When was the initial velocity that the ball was thrown at?

Answer 1

This is an inelastic collision

The velocity of the ball and box together can be computed by looking at the work done by friction

m*g*.24*.17=.5*m*v^2
m divides out
v=sqrt(2*9.81*.24*.17)
v=0.8947 m/s

knowing this, using conservation of momentum
110*v=(1011+110)*.8947
v=9.118 m/s

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