A balloon with mass `m` is descending down with an acceleration a `(where altg)` . How much mass should be removed from it so that it 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

Let upthrust of air be `F_(3)` them
For downward motion of balloon
`F_(a)=mg-ma`
`mg-F_(a)=ma`
For upward motion
`F_(a)-(m-Deltam)g=(m-Delta m)a`
Therefore `Delta m=(2ma)/(g+a)`