EasyPhysicsHigh School (11–12)Heat & Thermodynamics › Heat Engines, the Second Law and EntropyNumericalBoard ExamIB
An engine takes 4200 J of heat from its hot reservoir each cycle and gives 2940 J to the cold one…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
An engine takes of heat from its hot reservoir each cycle and gives to the cold one. Find the work per cycle and the efficiency. It runs at cycles each second. What is its power?
Need a reminder? The key ideaShow
A heat engine takes from a hot reservoir, does work and gives to a cold one: . A refrigerator uses work to take from the cold side: , and it gives to the warm side.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Work. .
Step 2. Efficiency. , or .
Step 3. Power. .
Answer: ; ; .
Check. of the heat, , goes to the cold reservoir.
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