Finding Joules of heat for 75% efficient motor at 250hp.

[Moose100]

Homework Statement

Forgive me for any indiscretions my first post.

The problem is to find the Joules of heat per hour produced in a motor that is 75% efficient and requires 0.250hp to run it.

Homework Equations

efficiency=1-(Qc/Qh)

The Attempt at a Solution

1. convert hp to Watts; 0.250hp* 746W/hp *75 percent=139W

At this point the answer is wrong and I don't know why. I have tried for hours to solve this please help!

 

[Mike Pemulis]

Try multiplying by 25 percent instead. 75% efficient means that 25% of the applied work is converted to heat.

 

[Moose100]

I did the problem is that gives me a small number at around 48 the bok says the answer is 168KJ


It's 139 when I multiply by 75%

 

[Mike Pemulis]

I don't know then. Would you mind typing out the problem exactly as it is stated?

 

[Moose100]

No problem.

How many joules of heat per hour are produced in a motor that is 75.0 percent efficient and requires 0.250hp to run it? Ans 168kJ