A moving neutron collides with a stationary α-particle. The fraction of the kinetic energy lost by the neutron is

Hero, we haveEi=12mu2  and  Ef=12mv2 As shown in the above question v=m1−m2m1+m2u or v=m−4mm+4mu  Fraction of energy lost =Ei−Ef/Ei =1−vu2=1−m−4mm+4m2 =1−926=1625