If a system performs 147 kJ of work while receiving 47 kJ of heat, what is change in its internal energy?

-100 kJ

Explanation:

We can solve this problem by applying the first law of thermodynamics, which states that:

where:

is the change in internal energy of a system

Q is the heat absorbed/released by the system (it is positive if absorbed by the system, negative if released by the system)

W is the work done by the system (it is positive if done by the system, negative if done on the system)

For the system in this problem we have:

W = +147 kJ is the work done by the system

Q = +47 kJ is the heat absorbed by the system

So , its change in internal energy is: