A monkey of mass m moving up on a massless string so as to just lift a block of mass M. After some time the monkey stops moving w.r.t the string. Find the magnitude of the change in the monkey's acceleration.

Explanation

When the monkey moves up with acceleration .a. to lift the block
`m(g+a)=Mg`
`a=((M-m)g)/(m)`
when monkey stops
`a^(1)=((M-m)g)/(M+m) therefore Delta a = a-a^(1)=(Mg(M-m))/(m(M+m))`