question_answer 24)

A bullet of mass 0.012 kg and horizontal speed  strikes a block of wood of mass 0.4 kg and instantly comes to rest with respect to the block. The block is suspended from the ceiling by means of thin wires. Calculate the height to which the block rises. Also estimate the amount of heat produced in the block.                                    [Chandigarh 07]  

Answer:

                Mass of bullet, m = 0.012 kg Speed of bullet, Mass of block, M = 0.4 kg If V is the velocity of the combination after collision, then from the law of conservation of momentum,   or                Let be the height through which the block rises. Then from the conservation of energy, P.E. of the combination = K.E. of the combination                 or            Amount of heat produced = Loss in K.E. of the bullet = Initial K.E. of the bullet                       - K.E. of the combination   = 29.4 - 0.86 = 28.54 J.