Find the size of Driving couple, if given the power?

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SUMMARY

The discussion centers on calculating the size of a driving couple when a shaft rotates at 3000 RPM and transmits 10,000 watts of power. The correct formula involves using the relationship between power, torque, and angular velocity. The participant initially calculated the torque as 9.54 Nm but later confirmed the correct value as 32 Nm after correcting a calculation error. The key takeaway is the importance of precise calculations in torque determination.

PREREQUISITES
  • Understanding of rotational dynamics
  • Familiarity with torque and power equations
  • Knowledge of angular velocity calculations
  • Basic proficiency in unit conversions (RPM to radians per second)
NEXT STEPS
  • Study the relationship between power, torque, and angular velocity in mechanical systems
  • Learn about the calculation of torque from power using the formula Torque = Power / Angular Velocity
  • Explore common mistakes in unit conversions and their impact on calculations
  • Review examples of driving couples in engineering applications
USEFUL FOR

Mechanical engineers, physics students, and anyone involved in rotational mechanics or power transmission calculations will benefit from this discussion.

alec433lawrid
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Homework Statement


Not really HW, just revision.

A shaft rotating at 3000 revolutions per minute is transmitting power of 10000 watts. find the size of the driving couple.


Homework Equations


Total wrk done by couple = 2.F.r.θ
Work = Torque . θ ( angle of rotation )
Power = work done / time

The Attempt at a Solution



60 seconds = 3000 revolutions
1 second = ?

Ans came to 50

Using ω = 2∏f resulted in ω = 100∏

Power = (Torque . θ)/t where θ/t = ω

Subject of the formula gave me 9.54 as an answer. When it should be 32Nm

What have I done wrong?
 
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welcome to pf!

hi alec433lawrid! welcome to pf! :smile:
alec433lawrid said:
Subject of the formula gave me 9.54 as an answer. When it should be 32Nm

i get 32

how did you get 9.54 ?​
 


Oh wow!, I am such a noob!

Sorry for wasting your time.

I did have the correct answer. ie my reasoning was correct. My calculator skills on the other hand let me down :(

I did 10000 / 100∏
when i should have done 10000 / (100 * ∏ )

It was a stupid mistake...
 

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