A system has an increase in internal energy of 60 J while 90 J was removed from the system by heat.How much work was involved during this process and was it done on the system or done on its environment?
A)30 J on the system
B)30 J on the environment
C)150 J on the system
D)150 J on the environment

Question

Quizplus · Accepted Answer

According to the first law of thermodynamics, energy can neither be created nor destroyed, only transferred between systems. Therefore, the total change in energy of the system is equal to the amount of heat added or removed from the system plus the amount of work done on or by the system. In this case, the internal energy of the system increased by 60 J while 90 J was removed from the system by heat. Therefore, the total change in energy of the system is -30 J. This means that 30 J of work was done on the system (since the sign of work done on the system is opposite to that of the change in energy of the system). Therefore, the correct choice is C, 150 J on the system.

A System Has an Increase in Internal Energy of 60