The velocity of a body revolving in a vertical circle of radius ‘r’ at the lowest point  7gr . The ratio of maximum to minimum tensions in the string is

given velocity at lowest point is v12=7gr---(1) we know that vθ=v12-2gr(1-cosθ) ⇒v2=v12-2gr(1+1) substitute given v12=7gr in above equation ⇒v22=7gr-4gr ⇒v22=3gr---(2) TmaxTmin=mv12r+mgmv22r-mg substitute eqn(1) & (2) TmaxTmin=8mg2mg TmaxTmin=41