Let's discuss a beautiful problem useful for Physics Olympiad based on Impulse and Momentum.
A particle of mass m is made to move with uniform speed v along the perimeter of a regular hexagon. Magnitude of impulse applied at each corner of the hexagon is
The velocity v is resolved into two components vcos60° and vsin60°
There will be no change of velocity along the sine component since they are all in same direction. Hence, the change of momentum will only be along the cosine component.
Change in momentum= mvcos60°-(-mvcos60°)=2mvcos60°=mv.
Since, magnitude of impulse is the change in momentum, the answer will be (a).