# Selina Solutions Class 9 Physics Solutions for Exercise 5C in Chapter 5 - Chapter 5 Upthrust In Fluids Archimedes Principle And Floatation

Question 12 Exercise 5C

A balloon filled with helium gas floats in a big closed jar which is connected to an

evacuating pump. What will be your observation, if air from the jar is pumped out? Explain your answer

The balloon will sink.

The density of air in the jar decreases as the air is pumped out from the jar. Hence the upthrust on the balloon decreases. The balloon sinks as the weight of the balloon surpasses the upthrust acting on it

Video transcript
hello everyone welcome to ludo this is priya and here we have a question about density and flotation let us look into the question a balloon filled with helium gas floats in a in a big closed jar which is connected to an evacuating pump what will be your observation if air from the jar is pumped out explain your answer coming to the answer of this question the ball the balloon which has filled with helium gas will sink this balloon will sink i will give you a reason why because the density of air in the jar decreases as the pump as the air is pumped out from the jar so with the help of evacuating pump when we when we are taking out the air from the jar the the density of air inside the jar also decreases density of air inside jar decreases as we are taking out the air from the jar with the help of evacuating pump hence the up thrust on the balloon also decreases because of this upthrust after balloon also decreases this will also decreases and the balloon sinks as the weight of the balloon surpasses the up thrusting acting on it if that a thrusting of the balloon has becoming down and decreasing more this makes the weight of the balloon to sink down hope you understand this video if you like the video please subscribe to our little channel and if you have any doubts you can keep a message in comment box thank you
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