How much torque must the pin exert to keep the rod from rotating?

AI Thread Summary
The discussion revolves around calculating the torque required from a pin to prevent a rod from rotating, given specific lengths and masses. Participants clarify that the point of rotation is indeed the pin, but emphasize that the pin can exert torque despite being at that point. The original poster struggles with the calculations, mistakenly using mass instead of force, which should include the acceleration due to gravity. A correction is suggested to multiply the mass values by the gravitational constant to obtain the correct force. Understanding the correct application of torque equations and forces is crucial for solving the problem accurately.
nweis84
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Homework Statement



How much torque must the pin exert to keep the rod from rotating?
(L=1.011m , M=3kg , m = .301kg)

So I am guessing the point of rotation is the pin??
But then how does the pin exert any torque if it is at the point of rotation?
I'm not quite sure


there is a sketch I've attached

Homework Equations



Ive used the equation \Sigma\taunet=0=\taupin-\tauM-\taum

The Attempt at a Solution


i have tried it so many ways and keep getting it wrong

\taupin = 3kg*(1.011m/2) + .301kg*1.011m
what am i doing wrong?
Please help thankyou
 

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For this type of problem, you probably don't need to worry about how the pin exerts a torque (though you can imagine in reality it would take a fair amount of force since there is only a small lever arm)

It looks like you've neglected to calculate the force of each of the masses and are using the mass instead (kg*m is not the units of force)
 


yeah thank you i did forget to multiply by the acceleration constant g
 
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