3. A 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 300 kJ of heat, and the paddle wheel does 50 kJ of work on the fluid. Determine the

final internal energy of the fluid. Neglect the energy stored in the paddle wheel.

Qout = 300 kJ

U₁ = 800 kJ

U₂ = ?

Fluid

Wsh.in = 50 kJ