A closed system of mass 20 kg undergoes a process..............?

Question

A closed system of mass 20 kg undergoes a process in which there is a heat tranfer of 1000 kJ from the system to the sorroundings. The work done on the system is 200 kJ. If the initial pecific internal energy of the sytem is 300 kJ/kg, what is the final specific internal energy, in kJ/kg? Neglect changes in kinetic and potebtial energy.

Answer 1

First Law of Thermodynamics:

dU = δQ - δW

where δQ is a small amount of heat added to the system, and δW is a small amount of work done by the system.

dU = -1000kJ - (-200 kJ)

dU = -800kJ

Since 20kg, each kg gains -800/20 = -40kJ.

So, 300 - 40 = 260kJ/kg