Question

A source supplies heat to a system at the rate of 1000 W. If the system performs work at a rate of 200 W, what is the rate at which internal energy of the system increases?

• A. 1200 W
• B. 600 W
• C. 500 W
• D. 800 W

Hint:

The first law of thermodynamics relates heat, work, and internal energy. Remember to apply this when solving energy balance problems.

Answer 1

The Correct Option is A

From the first law of thermodynamics: \[ \Delta U = Q - W \] Where \(Q\) is the heat supplied and \(W\) is the work done. Given that \(Q = 1000 \, \text{W}\) and \(W = 200 \, \text{W}\), the change in internal energy is: \[ \Delta U = 1000 - 200 = 1200 \, \text{W} \] Thus, the rate at which the internal energy increases is \(1200 \, \text{W}\).