A wooden boxcar is moving along a straight railroad track at
speed V1. A sniper fires a bullet (initial speed V2) at it from a high-powered
rifle. The bullet passes through both lengthwise walls of
the car, its entrance and exit holes being exactly opposite each
other as viewed from within the car. From what direction, relative
to the track, is the bullet fired? Assume that the bullet is not deflected
upon entering the car, but that its speed decreases by 20%.
Take Vi = 85 kmlh and V2 = 650 mls. (Why don't you need to
know the width of the boxcar?)

Question

A wooden boxcar is moving along a straight railroad track at
speed V1. A sniper fires a bullet (initial speed V2) at it from a high-powered
rifle. The bullet passes through both lengthwise walls of
the car, its entrance and exit holes being exactly opposite each
other as viewed from within the car. From what direction, relative
to the track, is the bullet fired? Assume that the bullet is not deflected
upon entering the car, but that its speed decreases by 20%.
Take Vi = 85 kmlh and V2 = 650 mls. (Why don't you need to
know the width of the boxcar?)

anonymous · Answer

I didn’t get the main idea of the problem. And why don’t we need the width of the boxcar?

anonymous · Answer

the hit only occur in normal direction,conserve moviment quantity(Q=m.v)

anonymous · Answer

it's not a momentum problem.

anonymous · Answer

Yeah, Algebraic is right. its a kinematic problem.

anonymous · Answer

Oh I got it. your sketch is almost right. I think this happens because the car is moving while the bullet is passing the width of the car:
|dw:1348364770007:dw|
so: $$V_2tsin \theta=V_1t \rightarrow \sin \theta=\frac{ V_1 }{ V_2}$$
after substituting we get θ=2.6°
thanks for help!