Question

A bullet of mass 10g is fired horizontally into a 5kg wooden block, at rest on horizontal surface. The coefficient of kinetic friction between the block and the surface is 0.1 Calculate the speed of the bullet striking the block, if the combination moves 20m before coming to rest.

Answer 1

Mass of bullet = 0.01 Kg and block = 5Kg total mass = 5.01kg Normal force = (m+M)*g = 5.01*9.8 = 49.098 N friction force = 0.1 * 49.098 = 4.9098N Suppose initial velocity = v hence change in kinetic energy = work done by frictional force 1/2 * (m+M) *v² = f *S 1/2 * 5.01 * v² = 4.9098 *20 v² = 98.196/ 2.505 v =√39.2 v = 6.26 m/s