A system receives 425 J of heat from the surroundings and
delivers 420 J of work to its surroundings. What is the change in
the internal energy?
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.