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A heat engine absorbs 893 J of energy per cycle from a high-temperature source. The...

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akjohnson95 | Student

Posted March 14, 2012 at 5:47 AM via web

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A heat engine absorbs 893 J of energy per cycle from a high-temperature source. The engine does 4.50X10^2 J of work during each cycle, expelling 4.43x10^2 J as heat.

What is the engine's efficiency?

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jeew-m | College Teacher | (Level 1) Educator Emeritus

Posted July 28, 2012 at 7:48 AM (Answer #1)

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Here input energy of 893 J was absorbed by the machine and give us a successful work of 450 J. From the rest 443 J are expelled as heat.

So efficiency = (successful work done)/(Energy input)*100%

                  = (450/893)*100%

                  = 50.39%

 

So the efficiency of the machine is 50.39%.

Note:

Always the efficiency of the machines are less than 100% due to the losses like heat, sound, vibration etc. If we use the expelling heat for another work we can increase the efficiency of the whole system.

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