Question

An electrically powered pump is used to pull water out of a well. In the course of an afternoon, the pump does 8.3 kJ of work lifting water out of a well. It also heats up, and releases 300 J of heat to the environment before returning to its original temperature. If there was no net change in the energy of the pump, how much electrical energy was required?

Answer 1

`E = 8.6 kJ`

Step-by-step explanation:

By energy conservation we know that

`E = U + W`

i.e. energy supplied by the pump is sum of the work done and increase in its internal energy

So here we know that

work done to pull the water from the well is given as

W = 8.3 kJ

also the increase in its internal energy is given as

`\Delta U = 300 J`

so total energy required is given as

`E = 8300 + 300`

`E = 8.6 kJ`