A block of mass 2.0 kg moving at 2.0 m/s collides head on with another block of equal mass kept at rest. (a) Find the maximum possible loss in kinetic energy due to the collision. (b) If the actual loss in kinetic energy is half of this maximum, find the coefficient of restitution.

Mass of the first block is m = 2kg


Initial speed before collision is u= 2 m/s


Mass of the second block is m’ = 2 kg


Final speed after collision is v


From law of conservation of momentum







{a} Loss in kinetic energy in elastic collision will be





{b} Actual loss = (maximum loss)/2 =2/2 =1J


Let final velocities of the blocks of masses 2kg are v1 and v2.


Where v1+v2=u and v1 - v2= eu.


Then, actual loss will be





Since, v1+v2=u and v1 - v2= eu







So, the coefficient of restitution (e) is


2