how do i do this physicsproblem?

myphonealmostdied

If the energy removed from an engine as heat

during one cycle is 5.0 × 102 J, how much

energy must be added to the engine during

one cycle in order for it to operate at 28

percent efficiency?

Answer in units of J.

fireman

As the efficiency is 28%=>the wastage is (100 - 28 = 72%)

=>Let the energy required to operate is M Jules/cycle

=>M x 78% = 5 x 10^2 J

=>M = 5 x 10^2 x 100/78 = 6.4 x 10^2 J/cycle

fazaldin-a

Here we have,

Heat energy = 5.0 x 102 J

efficiency = 28 %

Let Total Energy = E,

Then

5.0 x 102 x 100 / E = 28

E = 5.0 x 102 x 100 / 28 = 1821.43 J .................. Answer

shagda

-Number of loops x (Change in magnetic flux/change in time) x 100= percent efficency of engine