# Heat: efficiency

#### Dx

A heat engine has efficiency of 35% and recieves 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

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#### Tom Mattson

Staff Emeritus
Gold Member
Can you post the definition of efficiency from your book?

#### Dx

efficiency(e) = W(work out) / Q_H(work in)

#### Tom Mattson

Staff Emeritus
Gold Member
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!)

#### Dx

Originally posted by Dx
A heat engine has efficiency of 35% and recieves 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

Staff Emeritus
Gold Member
Yes, it does.

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