An electric heater supplies heat to a system at a rate of `100W`. If sustem performs work at a rate `74 Joul es` per second, at what rate is the internal energy increasing?

Explanation

Heat is supplied to the system at a rate of 100 W.
`therefore"Heat supplied", Q = 100 J//s`
The system performs at a rate of 75 `J//s.`
`therefore"Work done", W = 75 J//s`
From the first law of thermodynamics, we have:
`Q=U+W`
Where,
U=Internal energy
`thereforeU=Q-W`
`= 100 – 75`
`= 25 J//s`
`= 25 W`
Therefore, the internal energy of the given electric heater increases at a rate of 25 W.