Question

A balloon of gross weight w newton is falling vertically downward with a constant acceleration $a(<g)$. The magnitude of the air resistance is: (Neglecting buoyant force)

• A. $w$
• B. $w(1+\frac{a}{g})$
• C. $w(1-\frac{a}{g})$
• D. $w\frac{a}{g}$

Answer 1

The correct option is A $w$

$w=$ weight of the balloon

lets the air friction$=f$

The mass of the balloon , $m=\frac{w}{g}$

$a=$ constant acceleration with which balloon is falling.

The net force acting on the balloon is, $F_n=w-f$

$ma=w-f$

$\frac{w}{g}a=w-f$

$f=w(1-\frac{a}{g})$

if $a<g$ , then

$f=w$

Option A is correct.