An engine does 15kJ of work while rejecting 37 kJ to the cold reservoir. What is the efficiency of the engine?
Eff. = (Output/Input)*100%.
Eff. = (15/(15+37))*100% = 28.8%
The efficiency of an engine can be calculated using the formula:
Efficiency = (Work output / Heat input) * 100
Given that the engine does 15 kJ of work (W) and rejects 37 kJ of heat (Q), we can plug these values into the formula:
Efficiency = (15 kJ / (W - Q)) * 100
Efficiency = (15 kJ / (15 kJ - 37 kJ)) * 100
Efficiency = (15 kJ / -22 kJ) * 100
Efficiency = -68.18%
Therefore, the efficiency of the engine is approximately -68.18%.
To find the efficiency of the engine, we can use the formula:
Efficiency = (Work output / Energy input) * 100%
In this case, the work output is given as 15 kJ, and the energy input (which is the sum of the work output and the heat rejected) is given as 15 kJ + 37 kJ = 52 kJ.
Therefore, the efficiency of the engine can be calculated as:
Efficiency = (15 kJ / 52 kJ) * 100%
= 28.85%
So, the efficiency of the engine is approximately 28.85%.