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

by alec433lawrid
Tags: angluar velocity, power, torque
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alec433lawrid
#1
Mar9-12, 04:54 AM
P: 2
1. The problem statement, all variables and given/known data
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.


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

3. 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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tiny-tim
#2
Mar9-12, 05:02 AM
Sci Advisor
HW Helper
Thanks
tiny-tim's Avatar
P: 26,157
hi alec433lawrid! welcome to pf!
Quote Quote by alec433lawrid View Post
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 ?
alec433lawrid
#3
Mar9-12, 05:14 AM
P: 2
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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