A wagon of mass M can move without friction along horizontal rails. A simple pendulum consisting of a sphere of mass m is suspended from the ceiling of the wagon by a string of length L. At the initial moment the wagon and the pendulum are at rest and the string is deflected through an angle α from the vertical. Find the velocity of the wagon when the pendulum passes through its mean position.
When pendulum is deflected by 60 degree,height
raised be
h′=lcos60o=12
Change in height=l−l2=l2
Change in P.E=mgl2
12(m+M)V2=mgl2
Since mv=MV
V=mMV=mM√10mlm+M