Answer:
-50J
Explanation:
What is the first law of thermodynamics?
"The first law of thermodynamics state that energy is conserved"
the expression bellow is the Change in internal energy of a system
Change in internal energy of a system
= heat put into the system - work done by the system on its surroundings,
or
ΔU = ΔQ - ΔW.
given data
Work done=125J
Heat= 75J
change=?
Substituting we have
ΔU = 75- 125
ΔU = -50J
"ΔQ is positive if heat flows into the system, negative if it flows out of the system.
ΔW is positive if the system does work on its surroundings and it is negative if work is done on the system.
"
