Air is contained in a rigid well-insulated tank with a volume of 0.6 m3. the tank is fitted with a paddle wheel that transfers energy to the air at a constant rate of 4 w for 1 h. the initial density of the air is 1.2 kg/m3.
if no changes in kinetic or potential energy occur, determine:

(a) the specific volume at the final state, in m^3/kg
(b) the energy transfer by work, in kj.
(c) the change in specific internal energy of the air, in kj/kg.

0.833 m³/kg

-14.4 kJ

20 kJ/kg

Explanation:

= Density = 1.2 kg/m³

= Volume = 0.6 m³

t = Time taken = 1 hour

P = Power = 4 W

Mass is given by

As there is no change in kinetic and potential energy, the specific volume of the tank will be unaffected

The specific volume at the final state is 0.833 m³/kg

Energy is given by

The energy transfer by work is -14.4 kJ

Change in specific internal energy is given by

The change in specific internal energy is 20 kJ/kg

the part of the wave he is travelling on is the crest