A bob of mass m is attached to one end of the rod of negligible mass and length r, the other end of which is pivoted freely at a fixed centre O as shown in the figure. What initial speed must be given to the object to reach the top of the circle?

A bob of mass m is attached to one end of the rod of negligible mass a

1.	A bob of mass m is attached to one end of the rod of negligible mass and length r, the other end of which is pivoted freely at a fixed centre O as shown in the figure. What initial speed must be given to the object to reach the top of the circle?
Answer» Solution : ACCORDING to law of conservation of energy `(1)/(2)mv_(0)^(2)+0=0+mg(2r)` `v_(0)=sqrt(4gr)ms^(-1)` This value is LESS than `v_(1)=sqrt(5gr)` and greater than `v_(2)=sqrt(gr)`