In the figure shown the cart of mass '6m' is initially at rest. A particle of mass 'm' is attached to the end of the light rod which can rotate freely about A. If the rod is released from rest in a horizontal position shown, determine the velocity vrelof the particle with respect to the cart when the rod is vertical.
When the rod becomes vertical
mv1 = 6mv2⇒v1 = 6v2 .........(i)
12 mv21 + 126mv22 = mgl .........(ii)
Solve (i) and (ii) to get Vrel = v1 + v2 = √73gl