A pendulum bob of mass `m` connected to the end of material string of length `l` is released from rest from horizontal position as shown in the figure. At the lowest point the bob makes an elastic collision with a stationary block of mass `5m`, which is kept on a frictionless surface. Choose out the correct statement(s) for the instant just after the impact.

Answer

A, C, D

Explanation

Just after collision,
`v_m=((m-5m)/(m+5m))sqrt(2gl)=-2/3sqrt(2gl)`
`v_(5m)=((2xxm)/(m+5m))sqrt(2gl)=(sqrt(2gl))/(3)`
`T-mg=(mv_m^2)/(l)=m/l((8gl)/(9))`
`:. T=17/9mg`
`h_m=(v_m^2)/(2g)=(4l)/(9)`