A ball impinges directly upon another ball at rest and is itself brought to rest by the impact. If half of initial kinetic energy is destroyed in the collision, the coefficient of restitution is

Here,  u2=0                   v1=0From conservation of momentumm1u1=m2v2            1Final kinetic energy  12m2v22=1212m1u12                2From eq = (1)   12m2v2.ϑv=1212m1u1u1v2=12u1e=v2u1=12=0.5