Question

A helium balloon can just lift a load of 710 N. The skin of the balloon has a mass of 1.80 kg. What is the volume of the balloon?(the density of air is 1.29 kg/m³ and the density of helium is 0.179 kg/m³)

Answer 1

Weight of balloon + weight of load + weight of helium = weight of air displaced.

.

So...

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    1.8 * 9.80   + 710   + density of helium * volume * g  = density of air * volume * g

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      727.64   +    0.179 * V * 9.80   = 1.29 * V *9.80

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      727.64  +    1.7542 V =   12.642 V

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      727.64  =   10.8878 V

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   V =    66.83 m³