Question

A system releases 700 J of heat and does work. The change in internal energy (∆U) for the process is −460 J. The work done is ____________.

Options

• −460 J

• +240 J

• −250 J

• +460 J

Answer 1

A system releases 700 J of heat and does work. The change in internal energy (∆U) for the process is −460 J. The work done is +240 J.

Explanation:

Q = −700 J, ∆U = −460 J

According to the first law of thermodynamics;

∆U = Q + W

∴ W = ∆U − Q

= −460 J − (−700 J)

= +240 J