If a projectile hits a stationary target, and the projectile stops while the target moves at the same speed as the incoming speed of the projectile,
A)the mass of the projectile is much less than the mass of the target.
B)the mass of the projectile is equal to the mass of the target.
C)the mass of the projectile is much greater than the mass of the target.
D)nothing can be said about the masses of the projectile and target without further information.
E)this is an unphysical situation and will not actually happen.

Question

Quizplus · Accepted Answer

If the target moves at the same speed as the incoming speed of the projectile after it's hit, it means that the momentum of the two objects is conserved. Momentum is given by the product of mass and velocity, and since the velocity of the target is zero initially and after the collision, it means that the total momentum before and after the collision is the same. This can only happen if the mass of the projectile is equal to the mass of the target. Therefore, the correct answer is B, the mass of the projectile is equal to the mass of the target.

If a Projectile Hits a Stationary Target, and the Projectile