Answer to Question #154494 in Mechanics | Relativity for Kuldeep

Question

Rigid tank contains a hot fluid that is cooled while being stirred by a paddle wheel. Initially,  the internal energy of the fluid is 800 kJ. During the cooling process, the fluid loses 500 kJ of heat,  and the paddle wheel does 100 kJ of work on the fluid. Determine the final internal energy of the  fluid. Neglect the energy stored in the paddle wheel.

Answer 1

Energy balance:

$E_{in} -E_{out} = ΔE_{sys} \\ W_{paddle} -Q_{loss} = U_2 -U_1 \\ 100 -500 = U_2 - 800 \\ U_2 = 400 \;kJ$

Answer: 400 kJ