Question

A point mass having mass M is moving with a velocity V at an angle$\theta$ to the wall as shown in the figure. The mass undergoes a perfectly elastic collision with the smooth wall and rebounds. The total change (final minus initial) in the momentum of the mass is

• A. $-2MV\cos \theta \hat{j}$
• B. $2MV\sin \theta \hat{j}$
• C. $2MV\cos \theta \hat{j}$
• D. $-2MV\sin \theta \hat{j}$

Answer 1

The correct option is D $-2MV\sin \theta \hat{j}$


$P_i=MV\cos \theta \hat{i}+MV\sin \theta \hat{j}$

$P_i=MV\cos \theta \hat{i}-MV\sin \theta \hat{j}$

$P_f-P_i=-2MV\sin \theta \hat{j}$