A point particle is held on the axis of a ring of mass m and radius r at a distance r from its centre C . When released, it reaches C under the gravitational attraction of the ring. Its speed at C will be

Step-by-step solution

Let ' M ' be the mass of the particle Now, E _ initial = E _ final i.e. GMm 2 r +0= GM m r + 1 2 M ~V ^2 aligned & or, 1 2 M V^2= G M m r [1- 1 2 ] & 1 2 V^2= G m r [1- 1 2 ] & or, V= 2 G m r (1- 1 2 ) aligned