Finding Moment of Inertia of a wheel experimentally

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Discussion Overview

The discussion revolves around finding an experimental method to determine the moment of inertia (MOI) of wheels, particularly for bicycles and other vehicles. Participants explore different approaches and formulas related to this topic, including the use of energy equations.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Experimental/applied

Main Points Raised

  • One participant proposes a method involving a wheel, a string, and a free weight to calculate the MOI, presenting a specific formula for confirmation.
  • Another participant suggests that energy equations could also be used to verify the results, indicating an alternative approach to the problem.
  • A later reply acknowledges the relationship between the moment of inertia and angular acceleration, suggesting a connection to the proposed method.
  • One participant mentions the potential impact of friction on the calculations, indicating that it could be a significant factor in determining the MOI accurately.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the correctness of the proposed formula, and multiple approaches to calculating the moment of inertia are discussed without resolution.

Contextual Notes

Participants note the neglect of friction in the initial proposal, which could affect the accuracy of the results. There is also an acknowledgment of the need for further exploration of energy equations to validate the findings.

Loudhvx
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Hello all, and forgive me if I'm making newbie mistakes as I haven't posted here much.

I realize this appears to be a homework assignment, but it is not. I am trying to develop an easy method for determining the actual moment of inertia for real wheels, for bicycles and other vehicles. I googled the topic and many related results came up, but not explicitly for finding the MOI with a simple formula.

I believe I have the correct formula, but I need confirmation from more knowledgeable people. I made a pdf file summarizing the problem including a drawing. I hope the link works.

https://s3.amazonaws.com/loudfiles/MomentOfInertiaWheel_TEMP.pdf

All of the quantities are constant, as in not varying with time.
I neglect friction, but realize it can be a significant factor on a real wheel if not dealt with properly.

In case the link doesn't work, here is what I have:
A wheel of radius R is mounted with its axle horizontal.
A string is attached, and wrapped around the perimeter of the wheel (at radius R distance from the center).
The free end of the string is attached to a free-weight of mass M.
The free weight is allowed to fall a distance H, vertically, which accelerates the wheel.
The time it takes the weight to travel H is time t1.
g is the acceleration of gravity.

The MOI = ( (g t12 / 2 H) - 1 ) M R2

Can someone please confirm that for me? Thank you very much for your time.
 
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I forgot this can probably also be done using energy equations, so I forgive me, as that would have been a way I could check my results. If someone has that solution handy, that would be great as well. I will attempt that, but it will likely take me some time to brush up on those equations/concepts.
 
Perhaps see ...
 
Thanks. That does at least confirm the relationship of I to a.
 
You might be able to devise a way to take into account friction in your calculation of MOI.
 

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