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

Click For Summary

Homework Help Overview

The problem involves calculating the Joules of heat produced by a motor that operates at 75% efficiency and requires 0.250 horsepower. The context is centered around efficiency and energy conversion in mechanical systems.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • Participants discuss converting horsepower to watts and the implications of efficiency on heat production. There are attempts to clarify the calculations and the reasoning behind the efficiency percentage.

Discussion Status

The discussion includes various interpretations of the problem and attempts to clarify the calculations. Some participants suggest different approaches to the efficiency calculation, while others express confusion about the results obtained.

Contextual Notes

There is mention of a discrepancy between calculated values and expected answers, as well as a request for the exact wording of the problem statement to ensure clarity.

Moose100
Messages
116
Reaction score
0

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!
 
Physics news on Phys.org
Try multiplying by 25 percent instead. 75% efficient means that 25% of the applied work is converted to heat.
 
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%
 
I don't know then. Would you mind typing out the problem exactly as it is stated?
 
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
 

Similar threads

Burning fuel and a motor's efficiency
  • · Replies 2 ·
Replies
2
Views
1K
Thermodynamics problem involving engine efficiency
  • · Replies 20 ·
Replies
20
Views
3K
I calculating the heat exhausted from an engine.
  • · Replies 1 ·
Replies
1
Views
4K
Saving Electrical Energy with a Heat Pump: 75%
  • · Replies 1 ·
Replies
1
Views
2K
Heating a Cabaret during the winter
  • · Replies 4 ·
Replies
4
Views
2K
Joules required to heat/how much heat is released
  • · Replies 6 ·
Replies
6
Views
7K
Volume of water required to cool thermal/nuclear plants?
  • · Replies 3 ·
Replies
3
Views
2K
Power consumption in KWH of motor
  • · Replies 7 ·
Replies
7
Views
4K
Can You Solve These Challenging Physics Word Problems?
  • · Replies 7 ·
Replies
7
Views
3K
Rate body temperature increases given rate of heat transfer?
  • · Replies 1 ·
Replies
1
Views
7K