A balloon of weight w is falling vertically downward with a constant acceleration `a(gt g)`. The magnitude of the air resistance is

Options

A. w
B. `w(1+(a)/(g))`
C. `w(1-(a)/(g))`
D. `w(a)/(g)`

Answer

C

Explanation

( c) Suppose air resistance is F (upwards), then from equation of motion of balloon, we have
F=mass`xx`acceleration`=(W)/(g).a`
`therefore " " F=W(1-(a)/(g))`