A system receives 425 J of heat from the surroundings and

Question

delivers 420 J of work to its surroundings. What is the change in
the internal energy?

Answer 1

To find the change in internal energy, we need to use the first law of thermodynamics:

ΔU = Q - W

Where:
ΔU = Change in internal energy
Q = Heat absorbed by the system
W = Work done by the system

Given:
Q = 425 J (heat received from the surroundings)
W = -420 J (work done to the surroundings, negative because work done by the system is considered positive)

ΔU = 425 J - (-420 J)
ΔU = 425 J + 420 J
ΔU = 845 J

The change in internal energy is 845 J.