Question

A hydrogen gas filled balloon having a mass of 25 gram is released up in the air. as the balloon descends, the gas starts leaking from it with a uniform velocity of 12cm/s and as a result, The Balloon shrinks completely in 5s. find the average force acting on the balloon.

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Answer 1

The balloon loses 25 g or 0.025 kg gas in 5 s.

So, rate of flow of gas is, dm/dt = 0.025/5 = 0.005 kg/s

Velocity of the gas, v = 12 cm/s = 0.12 m/s

Now, rate of change of momentum is,

dP/dt = d(mv)/dt

=> F = v(dm/dt) + m(dv/dt)

=> F = v(dm/dt) + 0

=> F = 0.12(0.005) = 0.0006 N

Hope this will help you.... ✌

Answer 2

Answer:

-60dyne

Explanation:

Here, m= 25g u= 12 cm/s, v= 0, t=5 s

So, F= ma = m(v-u)/t = 25(0-12)/5 =-60 dyne

Also , I want to clear that please try to avoid f= ma when the question says mass is not constant, bcuz f= ma is valid only when mass is constant but here u can use that..

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