Conceptual question about torque and balls

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Homework Help Overview

The discussion revolves around a conceptual question regarding torque, specifically in relation to a ball and its interaction with the ground. The original poster is exploring whether torque can be measured from the point of contact between the ball and the ground, as opposed to the center of the ball.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to derive a relationship for torque using different reference points and questions the validity of their results. Other participants express confusion about the calculations and seek clarification on the correctness of the approach.

Discussion Status

The discussion appears to be ongoing, with participants expressing uncertainty about the calculations and seeking further input. There is a lack of suggestions or consensus on the matter, indicating that the topic is still open for exploration.

Contextual Notes

Participants are grappling with the implications of measuring torque from different points and the resulting equations. There is an indication of confusion regarding the outcomes of their calculations, which may stem from assumptions about the system being analyzed.

Niles
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[SOLVED] Conceptual question about torque and balls

Homework Statement


Take a look at the following thread:

https://www.physicsforums.com/showthread.php?t=147053

In this thread, the torque is measured from the center of the ball. Can I measure it from the point where the ball and the ground touch each other, so the torque is:

T = mgsin(a)*R = I*alfa?

I tried, and it gives me that a = (3/2)gsin(a), which is wrong - why?
 
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No, then again I get (2/3) rather than (3/2) - but still it doesn't work.
 
Any suggestions? I would really like to know, whether am I wrong or right about this.
 
No suggestions at all :)?
 

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