Question

A student does 1,000 J of work when she moves to her dormitory. Her internal energy is decreased by 3,000 J. Determine the heat during this process. Does she gain or lose her heat?

Answer 1

-2000 J (heat lost)

Step-by-step explanation:

We can solve the problem by using the 1st law of thermodynamics:

`\Delta U = Q-W`

where

`\Delta U` is the change in internal energy of a system

Q is the heat absorbed by the system

W is the work done by the system

In this situation, we have

`W=1000 W` (work done by the student)

`\Delta U = -3000 J` (decrease in internal energy)

So the heat is

`Q=\Delta U + W = -3000 J +1000 J = -2000 J`

And the negative sign means the student has lost heat.