The change in internal energy equals the sum of the heat supplied and the work done on the gas.
Symbols
ΔU
change in internal energy
[J]
Q
heat
[J]
W
work
[J]
Where it comes from
This is the conservation of energy for a gas — the internal energy increases by the heat supplied and by the work done on the gas. Heat and work are two ways of transferring energy.
When to use it
Gas processes, heat engines, refrigerators.
Example
500 J of heat is supplied to a gas and 200 J of work is done on it. Calculate the change in internal energy.