physics qts. plz help?

Question

A particular engine has a power output of 6.00 kW and an efficiency of 25.0%. Assume the engine expels 8500 J of energy in each cycle.
(a) Find the energy absorbed in each cycle.
(b) Find the time required to complete each cycle.

Answer 1

The energy absorbed is that which is not outputted. In this case, 75% of the energy is absorbed, so the energy absorbed per cycle is .75*8500 J. One watt = 1J/sec. So seconds = J/watt. The power is constant, so the power in each cycle is 6,00 kW; this times the duration of the cycle will be the energy in each cycle.

Answer 2

You can approach this question as a simple maths problem.

a)8500J is actually 75% of total energy output in ONE CYCLE. Energy absorbed is thus 25% of total energy output.

b) 6.00kW actually means energy output in one hour is 6000J. From a), get your answer for 100% of total energy output in ONE CYCLE. From there, calculate how many cycles can be completed in one hour with 6000J of energy. Lastly, find out time taken for one cycle.

Hope this helps!