## Question

If a room has dimensions , what is the mass of air in the room if density of air at NTP is 1.3 kg/m^{3}?

[Density of water is 10^{3} kg/m^{3} and g = 10 m/s^{2}]

### Solution

78 kg

As density is defined as the ratio of mass to volume, i.e.,

= 78 kg.

i.e., mass of air in the room is 78 kg which is unbelievable (as air is assumed to be weightless) but is true.

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,

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