How Does Friction Affect Energy Conservation in Rotational Motion Experiments?

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Homework Help Overview

The discussion revolves around an experiment involving rotational motion and energy conservation, specifically examining how friction impacts energy calculations. Participants are tasked with formulating an energy conservation equation that incorporates various forms of energy and the energy lost due to friction.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to set up an energy conservation equation but expresses confusion regarding the role of friction in energy loss. Some participants question the validity of the terms used in the equation, particularly how friction is represented. Others seek clarification on the relationship between torque and energy in this context.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the energy equation. Some guidance has been offered regarding the representation of friction, but there is no clear consensus on the correct approach or formulation at this stage.

Contextual Notes

Participants are working under the constraints of a classroom experiment and are required to adhere to specific homework guidelines, which may limit the information they can use or assumptions they can make.

Painguy
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Homework Statement


We performed a small experiment in class which had us attach a mass to a string which hung on a pulley which led to a rotating object.
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We were then told to write down a conservation of energy equation stating that the initial energy is equal to the final energy. We were asked to include kinetic energy (rotational, translational), potential energy, and energy lost due to friction which we found with Tf=f*r.


Homework Equations




The Attempt at a Solution



This is what I have setup so far.

Ui +Kroti +Ktransi=Uf+Krotf +Ktransf +Wf

mgd=.5Iw^2 + .5mv^2 -f

I'm still a little confused about how energy is conserved if we're losing energy due to friction?

After that they ask me to replace every instance of w with v/r and v with 2d/t and try to get the following I=(mr^2)((gt^2/2d)-1-(t^2/(2md))f)

What am I doing wrong here?
 
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Painguy said:
mgd=.5Iw^2 + .5mv^2 -f
f is the force of friction? If so, there are two things wrong with the -f term.
 
how in the world are you equating torque with energy
 
haruspex said:
f is the force of friction? If so, there are two things wrong with the -f term.
I suppose I should have did f*Δd? I'm not sure what to do here.
 

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