Question 5: What happens to the KE of the bullet when it penetrates into the target? ANSWER When a bullet of mass ‘m’ is moving with velocity ‘v’ it possesses kinetic energy given by, When this bullet hits the target, it penetrates into the target and comes to rest after penetrating into the target for some distance. When it comes to rest, the final velocity is 0 m/s. In this way, the final K.E also becomes zero? The question is what happens to the initial K.E of the bullet? The kinetic energy possessed by bullet as given in the above equation is exhausted mostly in the work done against the resistance offered by the target while penetrating into it. Some part of the kinetic energy may also have lost as heat and sound.