Question

A system's thermal energy decreases by 20 J while the system performs 10 J of work. How much heat was added to the system?

Answer 1

Q = -10J

Step-by-step explanation:

The change in internal energy is equal to the heat added to the system less the work done by the object, so:

ΔU = Q - W

Then, replacing the change in internal energy ΔU by = - 20J and W by 10J, we get:

-20J = Q - 10J

Add 10J to both sides of the equation:

-20J + 10J = Q - 10J + 10J

-10J = Q

Therefore, the answer is Q = -10J