Answer to Question #60673 in Mechanics | Relativity for Sakura

Question

An unconstrained rifle of mass 5.00kg fires a 50.0g bullet at a speed of 300.0m/s with respect to the ground.

a) What is the initial momentum of the rifle-bullet system?
b)What is the recoil velocity of the rifle?

Answer 1

a) before the shot fired, both the rifle and the bullet are at rest, so their momentums are zero: therefore, the total momentu, of the system is zero
b) the total momentum of the system remains zero;
M(bullet) x V(bullet) + M(rifle) x V(rifle) = 0;
V(rifle) = M(bullet) x V(bullet) / M(rifle);
V(rifle) = 0.05 x 300 / 5 = 3 m/s