Question

An empty room measures 5m * 4m * 2.5m. if the density of air is 1.3kg/m³ , what is the mass of the air in the room?

Answer 1

Volume of room= l*b*h
                         =5m * 4m * 2.5m 
                         =50m³
we know, density=mass / volume
then, 1.3kg/m³=mass/50m³
Mass= 1.3 x 50 kg
        = 65 kg

∴mass= 65kg

Answer 2

Density = mass
               volume

density = 1.3 kg/m³
volume =

l x b x h

=5 x 4 x 2.5
= 50m²
--------------------------
mass = density x volume
             

= 1.3x50

=65 kg
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mass of the air in the room is 65 kg