Question

A balloon has 2 g of air. A small hole is pierced into it. The air comes out with a velocity of 4 m/s.If the balloon shrinks completely in 2.5 s. The average force acting on the balloon is

• A. 0.0008 N
• B. 0.0032 N
• C. 8 N
• D. 3.2 N

Answer 1

The correct option is B 0.0032 N

force equals to the time rate of change of momentum
i.e F = P/t where P = mv (m=mass , V =velocity)
F = mv/t = (0.002kg × 4 m/s)÷ 2.5 sec
F = 3.2 × 10^-3 N = 0.0032 N