Question

An engine is found to have an efficiency of 0.40. If it does 200 J of work per cycle, what are the corresponding quantities of heat absorbed and discharged?

a) 300 J absorbed, 100 J discharged
b) 80 J absorbed, 120 J discharged
c) 120 J absorbed, 80 J discharged
d) 50 J absorbed, 150 J discharged

Answer 1

The engine with an efficiency of 0.40 absorbs 500 J of heat and discharges 300 J of heat per cycle when it does 200 J of work.

Step-by-step explanation:

To determine the quantities of heat absorbed and discharged by an engine with an efficiency of 0.40 that does 200 J of work per cycle, we use the formula for efficiency:

efficiency = work output / heat absorbed.

Since we know the efficiency (0.40) and the work output (200 J), we can solve for the heat absorbed:

Efficiency = Work output / Heat absorbed
=> 0.40 = 200 J / Heat absorbed
=> Heat absorbed = 200 J / 0.40
=> Heat absorbed = 500 J.

Now, to find the heat discharged, we use the conservation of energy principle, which states that the total energy remains constant. Therefore, the heat discharged is the difference between the heat absorbed and the work output:

Heat discharged = Heat absorbed - Work output
=> Heat discharged = 500 J - 200 J
=> Heat discharged = 300 J.

Thus, the engine absorbs 500 J of heat and discharges 300 J of heat per cycle.