Question

Military rifles have a mechanism for reducing the recoil forces of the gun on the person firing it. An internal part recoils over a relatively large distance and is stopped by damping mechanisms in the gun. The larger distance reduces the average force needed to stop the internal part.

(a) Calculate the recoil velocity of a 1.00-kg plunger that directly interacts with a 0.0200-kg bullet fired at 600 m/s from the gun.

Answer 1

To calculate the recoil velocity of the plunger, conservation of momentum is used, resulting in a recoil velocity of -12 m/s, indicating the direction opposite to the bullet's motion.

Step-by-step explanation:

The student's question involves the conservation of momentum to calculate the recoil velocity of an internal part of a military rifle, which is a typical physics problem encountered in high school or introductory college physics courses.

To calculate the recoil velocity (vplunger) of the 1.00-kg plunger, we use the law of conservation of momentum, which states that the total momentum before the bullet is fired is equal to the total momentum after the bullet is fired. Initially, the system (bullet + plunger) is at rest, so the total momentum is 0. After the bullet is fired:

(mass of bullet × velocity of bullet) + (mass of plunger × velocity of plunger) = 0

(0.0200 kg × 600 m/s) + (1.00 kg × vplunger) = 0

Solving for vplunger, we find:

vplunger = - (0.0200 kg × 600 m/s) / 1.00 kg = -12 m/s

The negative sign indicates that the plunger is moving in the opposite direction of the bullet, which is the recoil effect.