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. The rate at which internal energy of the system increase is

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

Answer 1

The Correct Option is C

To solve this problem, we use the First Law of Thermodynamics, which is expressed as:

Q = \Delta U + W

where:

• Q is the heat supplied to the system.
• \Delta U is the change in internal energy of the system.
• W is the work done by the system.

In this question:

• The rate of heat supplied, Q, is given as 1000 W.
• The rate of work done by the system, W, is given as 200 W.

We are required to find the rate at which the internal energy of the system increases, which means we need to calculate \Delta U.

Rearranging the formula for the rate of change of internal energy, we get:

\Delta U = Q - W

Substituting the given values:

\Delta U = 1000 \, \text{W} - 200 \, \text{W} = 800 \, \text{W}

Thus, the rate at which the internal energy of the system increases is 800 W.

The correct answer is 800 W. The other options are incorrect as they do not match the computation based on the given values and the formula.