To estimate the required torque

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    Estimate Torque
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Discussion Overview

The discussion revolves around calculating the torque required to lift a mass using a pulley system. Participants explore the relationship between force, radius, and torque, as well as the implications of pulley dimensions on torque and rotational dynamics.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Conceptual clarification

Main Points Raised

  • One participant states that torque can be calculated using the formula T = f * r, where f is the force and r is the radius of the pulley.
  • Another participant points out that the radius of the pulley is 26mm and provides the formula for torque, questioning if that is sufficient for the calculation.
  • There is a discussion about whether the gravitational constant "g" is necessary in the torque calculation since the force is already given in Newtons.
  • One participant inquires about the relevance of the equation T = I * α, suggesting it applies when the pulley has mass and is accelerating.
  • Another participant questions the effect of increasing the width of the pulley, noting that the width does not appear in the torque equation.
  • A later reply suggests that increasing the width would increase the moment of inertia (I) of the pulley, which could affect the dynamics despite width not being directly included in the torque equation.

Areas of Agreement / Disagreement

Participants express differing views on the implications of pulley width and mass on torque calculations, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Participants have not fully resolved the implications of the moment of inertia in relation to the width of the pulley, and there are assumptions regarding the mass and acceleration of the pulley that are not explicitly detailed.

Who May Find This Useful

This discussion may be useful for individuals interested in mechanical engineering, physics students studying rotational dynamics, or anyone exploring the principles of torque in pulley systems.

ravipatil666
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a mass of 100N has to be lifted up via string attached to pulley.
What is the torque required to rotate that pulley
 
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Welcome to PF!

ravipatil666 said:
a mass of 100N has to be lifted up via string attached to pulley.
What is the torque required to rotate that pulley

Hi ravipatil666! Welcome to PF! :smile:

Torque = distance "cross" force …

so what is the radius of the pulley? :wink:
 
the pulley has 26mm radius..
f=m*g
r=.026
and T=f*r (N-m)
thats it?
 
and thanks 4 my post tiny-tim
 
ravipatil666 said:
the pulley has 26mm radius..
f=m*g
r=.026
and T=f*r (N-m)
thats it?

Yup! It's as easy as that! :biggrin:

(except that you don't need the "g", since the mass is given to you in Newtons, not kg, anyway :wink: )
 
oh you my mistake...
 
and i want to know when does the eq T=I*alpha
comes into picture?
 
and also 1 more question
wht happens if the width of the pulley s increased?
bcoz width has nothing to do in the eq only radius s considered.
 
ravipatil666 said:
and i want to know when does the eq T=I*alpha
comes into picture?

(have an alpha: α :wink:)

ah, that's only if the pulley has non-negligible mass, and you want to find how fast it's rotating …

I is the moment of inertia of the pulley, and α is the angular acceleration. :wink:
ravipatil666 said:
wht happens if the width of the pulley s increased?

nothing … only the radius matters. :smile:
 
  • #10
Increasing the width of the pulley will require more material which will increase the value of I, so the change will show up there, even though the width does not appear directly in any of the equations you have written.
 
  • #11
thanks(dhanyawaad)...
 

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