A CD player and its battery together do 500 kJ of work .The battery also releases 250 kJ of energy as heat and the CD player releases 50 kJ as heat due to friction from spinning.What is the change in internal energy of the system,
With the system regarded as the battery and CD player together?

Question

Quizplus · Accepted Answer

The total energy released as heat is 250 kJ + 50 kJ = 300 kJ. The work done is 500 kJ. The change in internal energy is the work done minus the heat released: 500 kJ - 300 kJ = 200 kJ. Since the system loses energy, the change is negative: -200 kJ.

A CD Player and Its Battery Together Do 500 KJ