Question

A balloon of mass M is descending at a constant acceleration a. When a mass m is
released from the balloon, it starts rising with the same acceleration a.Assuming
that its volume does not change, what is the value of m?

Answer 1

Mg - f = Ma

f = M(g-a) _(1)

f - (M-m)g = (M-m)a _(2)

using (1) in (2)

M(g-a) - M(g+a) = -m(g+a)

m=2Ma/a+g