A bullet having a mass of 550 g travels at a velocity of 800

A bullet having a mass of 55.0 g travels at a velocity of 800 m/sec. This bullet impacts a stationary wooden block having a mass of 12.70 kg, and the bullet remains inside the block. What is the velocity of the block-bullet combination after impact?

Solution

Mass of bullet m = 55 g = 0.055 kg

Initial velocity of bullet u = 800 m/s

mass of wooden block M = 12.7 kg

Initial velocity of wooden block U = 0

Let the velocity of the block-bullet combination after impact v = ?

From law of conservation of linear momentum ,

mu + MU =(m+M) v

           mu =(m+M) v         Since U = 0

             v = mu /(m+M)

               = (0.055x800)/(0.055+12.7)

               = 3.449 m/s