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Question:

A gas is compressed from a volume of 2m³ to a volume of 1m³ at a constant pressure of 100 N/m². Then it is heated at constant volume by supplying 150 J of energy. As a result, the internal energy of the gas:

Increases by 250 J

Increases by 50 J

Decreases by 250 J

Decreases by 50 J

Solution:

ΔU = Q + W
ΔU = Q + PΔV
ΔU = 150 + 100(1 - 2)
ΔU = 50 J
As the value is positive, internal energy of the gas increases by 50 J