An electric heater supplies heat to a system at a rate of 100W. If sys

1.	An electric heater supplies heat to a system at a rate of 100W. If system performs work at a rate of 75 joule per second, at what rate is the internal energy increasing?
Answer» Heat supplied, ∆Q = 100W = 10OJs^-1 Useful work done, ∆W = 75J s^-1 Using first law of thermodynamics ∆Q = ∆U+ ∆W ∆U = ∆Q – ∆W = 100Js^-1 – 75Js^-1 = 25Js^-1.

An electric heater supplies heat to a system at a rate of 100W. If system performs work at a rate of 75 joule per second, at what rate is the internal energy increasing?

Answer»

Heat supplied, ∆Q = 100W = 10OJs^-1

Useful work done, ∆W = 75J s^-1

Using first law of thermodynamics

∆Q = ∆U+ ∆W

∆U = ∆Q – ∆W

= 100Js^-1 – 75Js^-1 = 25Js^-1.