A military gun is mounted on a railroad car (m = 1500 kg). There is no frictional force on the car, the track is horizontal, and the car is initially at rest. The gun then fires a shell of mass 30 kg with a velocity of 300 m/s at an angle of 40° with respect to the horizontal. Find the recoil velocity of the car.
Using Pi=Pf, I plugged in
0=30*300+1500v
to get V=-6 m/s.
I don't quite understand where the angle comes into play to solve this. Am I doing this right?
1 answer
The angle is relevant because only the horizontal component of the recoil is applied to the railroad car. Basically, you calculate the impulse delivered by firing (equal to the momentum of the shell), multiply it by the cosine of 40 degrees, to get the horizontal impulse delivered to the railroad car. Then, find what velocity that impulse would correspond to for the railroad car.
1 answer