Question

A turbine takes in 1000j of energy from fuel to supply 650j of work which is used to power a generator. The energy removed as heat to a cooling system will raise the temperature of .10 kg of water 1.2C. Are these figures consistent with the first and second law of thermodynamics & is this an efficient project?

Answer 1

First law of thermodynamics - Energy can be transformed from one form to another form , but can niether be created nor be destroyed. which means that egergy given / taken in = work done + energy released

now according to the given question energy taken in = 1000j

and work done = 650j

so energy released should be = 1000 - 650

= 350 j ................( A )

but energy removed as a heat will raise the temperature 0f mass " m " = 0.10 kg = 100 gm , of water which specific heat is 4.186 j / gm 0C , to the temperature 1.2 0C .

so the heat required to raise the temperature of the water "Q" = m s * raise in temperature

Q = 100 * 4.186 * 1.2 = 502.32 j .........( B )

FROM equatin A and B it is clear that this project violates the law of conservation of energy .

therefore this porject is not efficient .