A balloon with mass m is descending down with an acceleration a (where a < g). how much mass should be removed from it so that it starts moving up with an acceleration a

Q: A balloon with mass m is descending down with an acceleration a (where a < g). how much mass should be removed from it so that it starts moving up with an acceleration a

(a) ma/(g+a)

(b) ma/(g- a)

(c) 2ma/(g+a)

(d) 2ma/(g- a)

Ans: (c)