• # question_answer A particle of mass m strikes a wall at an angle of incidence $60{}^\circ$ with velocity b elastically. The impulse is A) $mv$                          B) $m\frac{v}{2}$C) $-2\,m\,v$                   D)  0

Impulse = change in momentum $=mv\cos {{60}^{o}}-(-mv\cos {{60}^{o}})$ $=2mv\,\cos {{60}^{o}}=2mv(1/2)=mv$ Hence, the correction option is [a].