At a training exercise, a policeman fires a pistol. A bullet of mass 10.0 g leaves the pistol horizontally at a speed of 500 ms-1. The bullet strikes and gets embedded in a stationary piece of wood of mass 1.0 kg which was suspended. Immediately after impact, the wood with the embedded bullet moves at a horizontal speed of 5.0 ms-1 and swings upwards to a vertical height of h from its initial position before stopping momentarily.
a) What is the initial kinetic energy of the bullet when it leaves the pistol?
b)What is the final kinetic energy of the wood and embedded bullet immediately after impact?
c) By comparing (a) and (b), what is the loss in kinetic energy? Account for this loss.
d) Calculate the vertical height, h, stating any assumption made. Assume the gravitational field strength is 10 N kg-1.
a) 1250 J
b) 12.6 J
c) 1240 J. The loss in kinetic energy is converted to heat and sound energy when the bullet strikes the wood and is embedded.
d) 1.25 m