In a certain thermodynamic process,20 cal of heat are removed from a system and 30 cal of work are done on the system.The internal energy of the system
A)increases by 10 cal.
B)decreases by 10 cal.
C)increases by 50 cal.
D)decreases by 50 cal.
E)decreases by 20 cal.

Question

Quizplus · Accepted Answer

The first law of thermodynamics states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. In this case, heat is removed (which is equivalent to negative heat being added), and work is done on the system (which can be considered as negative work done by the system). Therefore, the change in internal energy is -20 cal (for the heat removed) - (-30 cal) (for the work done on the system), which equals +10 cal. This means the internal energy increases by 10 cal.

In a Certain Thermodynamic Process,20 Cal of Heat Are Removed