A ballon with mass 'm’ is descending down with an acceleration ‘a' (where `a le g`). How much mass should be removed from it so that is starts moving up with an acceleration ‘a ’ ?

Options

A. `(2ma)/(g+a)`
B. `(2ma)/(g-a)`
C. `(ma)/(g+a)`
D. `(ma)/(g-a)`

Answer

A

Explanation

from figure (2)
F- (m-m) g = (m-m) a where m= m - m
mg - ma - mg + mg = ma = m a
mg + ma = ma
m(g + a ) = 2 ma
`m= (2ma )/( g+ a)`