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A closed system of constant volume experienced a temperature rise of 20°C when certain process occurs. The heat transfer in the process is 25 kJ. The specific heat at constant volume for the pure gas is 2 kJ/kg°C and system contains 2 kg of this substance. Determine the work done during this process.

A closed system of constant volume experienced a temperature rise of 20°C when certain process occurs. The heat transfer in the process is 25 kJ. The specific heat at constant volume for the pure gas is 2 kJ/kg°C and system contains 2 kg of this substance. Determine the work done during this process. Correct Answer -55 kJ

Concept: 

From the first law of thermodynamic, the heat supplied to the system can be utilized to change the internal energy of the system and help the system to do the work. Mathematically it can be expressed as,

Q = dU + W

Calculation:

Given:

ΔT = 20°C, Q = 25 kJ, Cv = 2 kJ/kg°C, m = 2 kg

25 = (2 × 2 × 20) + W

W = - 55 kJ

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