Question

Sixty-three joules of heat are added to a closed system. The initial internal energy of the system is 58 J, and the final internal energy is 93 J.How much work is being done by the system?28 J30 J88 J151 J

Answer 1

The energy equation for closed systems is:

`Q-W=\Delta U`

where:

• Q is the heat transfer to the system.

,

• W is the work done by the system.

,

• ΔU is the change of internal energy of the system.

In this case we know that the heat transfer is 63 J, the initial internal energy and final internal energy are 58 J and 93 J, respectively; plugging these values in the equation above and solving for the work we have:

`\begin{gathered} 63-W=93-58 \\ W=63-93+58 \\ W=28 \end{gathered}`

Therefore, the work done by the system is 28 J