The Efficiency of Heat Engines: Calculating Work Output from 150J Heat Input

In summary, the conversation discusses a question about a heat engine with an efficiency of 35% and receiving 150J of heat per cycle. The calculation for work performed in each cycle is done, with the answer being 52.5J. However, there is some confusion about whether the heat input should be 150J or something else, and the definition of efficiency is mentioned.
  • #1
Dx
A heat engine has efficiency of 35% and receives 150J heat per cycle. how much work dos it perfrom in each cycle?

I said 52.5J

w=e*q_h =
.35 * 150 =
52.5
its wrong

what did i do wrong with this calculation. unless it mean 150J of put in. can anyone please explain this to me.
TY!
dx :wink:
 
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  • #2
Can you post the definition of efficiency from your book?
 
  • #3
efficiency(e) = W(work out) / Q_H(work in)
 
  • #4
Originally posted by Dx
efficiency(e) = W(work out) / Q_H(work in)

That's what I thought. OK, just plug-n-chug.

(You know, it's always possible that the book is wrong!)
 
  • #5
Originally posted by Dx
A heat engine has efficiency of 35% and receives 150J heat per cycle. how much work dos it perfrom in each cycle?

I said 52.5J

w=e*q_h =
.35 * 150 =
52.5

I thought i did that like shown but aparently its not right. I just wanted to know does your answer match mine?
Dx:wink:
 
  • #6
Yes, it does.
 

What is a heat engine?

A heat engine is a device that converts thermal energy (heat) into mechanical work. It typically works by using the temperature difference between a high-temperature source and a low-temperature sink to drive a cyclical process.

How is the efficiency of a heat engine calculated?

The efficiency of a heat engine is calculated by dividing the work output by the heat input. In other words, it is the ratio of the amount of useful work produced by the engine to the amount of heat energy that is supplied to it.

What is the formula for calculating work output from heat input?

The formula for calculating work output from heat input is: Work output = Heat input - Heat output. In other words, the work output is equal to the difference between the amount of heat energy that is supplied to the engine and the amount of heat energy that is exhausted by the engine.

What factors can affect the efficiency of a heat engine?

The efficiency of a heat engine can be affected by a number of factors, including the internal resistance of the engine, the temperature difference between the source and sink, and the type of working fluid used in the engine. Other factors such as friction and heat losses can also play a role in reducing the efficiency of a heat engine.

Why is it important to calculate the efficiency of a heat engine?

Calculating the efficiency of a heat engine is important because it allows us to determine the amount of useful work that can be extracted from a given amount of heat energy. This information can be useful in designing more efficient engines and improving the overall efficiency of energy production processes.

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