A is a fixed point at height H above a perfectly inelastic smooth horizontal plane. A light inextesnsible string of length `L(gtH)` has one end attached to A and other to a heavy particle. The particle is held at the level of A with string just taut and released from rest. Find the height of the particle above the plane when it is next instaneously at rest .

Answer

D

Explanation

In perfectly inelastic collision with the horizontal surface the component parallel to the surface will remain unchanged. Similarly when the string becomes taut again, the component perpendicular to its length will remain unchanged.

`cos theta=H/Limpliesv_c=sqrt(2gH)`
`v_cos^(2)theta=(sqrt(2gH))H^2/L^2=v` (say)
`:. h=(v^2)/(2g)=((2gH)H^4/L^4)/(2g)=H^5/L^4`