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

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SUMMARY

The discussion focuses on calculating the Joules of heat produced by a motor that operates at 75% efficiency and requires 0.250 horsepower (hp). The correct calculation involves converting horsepower to Watts, resulting in 186.75 Watts (0.250 hp * 746 W/hp). Given the efficiency, 25% of the input energy is converted to heat, leading to a total heat output of 168 kJ per hour, confirming the textbook answer.

PREREQUISITES
  • Understanding of horsepower to Watts conversion
  • Basic knowledge of efficiency calculations
  • Familiarity with thermal energy concepts
  • Ability to manipulate equations involving heat transfer
NEXT STEPS
  • Study the principles of thermodynamics related to efficiency
  • Learn about energy conversion and power calculations
  • Explore heat transfer mechanisms in electrical motors
  • Investigate the implications of motor efficiency on energy consumption
USEFUL FOR

Engineering students, electrical engineers, and anyone involved in motor design or energy efficiency analysis will benefit from this discussion.

Moose100
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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!
 
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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
 

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