Solving the Billiard Ball Problem: Finding Work Lost to Friction

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Homework Help Overview

The discussion revolves around a physics problem involving a billiard ball that is initially spinning and slipping on a table. The problem requires determining the work lost to friction during the slipping phase, using two different methods that should yield the same result. Key parameters include the radius, mass, initial angular speed, forward speed, and the coefficient of kinetic friction.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to use equations of motion and torque to find the acceleration and angular acceleration of the ball. They raise questions about the validity of using certain kinematic equations to find the distance the ball slips and whether final speeds should be calculated or used from previous results.

Discussion Status

The discussion is ongoing, with some participants seeking clarification on the problem setup, particularly regarding the axis of rotation of the ball. There is a lack of consensus, as some participants express confusion about the problem statement and its physical implications.

Contextual Notes

Participants are working under the constraints of a homework assignment, which may limit the information they can share or the methods they can use. The original poster has provided specific parameters but has not fully clarified the setup, leading to questions about assumptions regarding the ball's motion.

aldee11
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Billiard ball rotating and slipping. help

Homework Statement


A ball radius "a" and mass "m" initially spinning counterclockwise with angular speed w=-v0/a with a forward speed vo. The coefficient kinetic friction between the ball and the billiard table is Mu, [Given a,m,vo,mu]
Determine the work lost to friction while slipping using two methods (they should be equal)
W=-Ffs where s the distance ball slips not travels
W= delta Kt + delta Kr


Homework Equations


F=ma
Torque= I*alpha
W=v/r
V=vo+at
W=Wo+alpha*t



The Attempt at a Solution



I found a from equation F= ma where F=-Ff
Then plug in a to eq V=Vo+at

I also found alpha from eq Torque= I alpha
then plug in alpha to eq W=Wo+ alpha t

set V=RW i got T where the slipping becomes rolling without slipping.

The questions are
1. Can i use this t and plug it into eq X=Xo+volt+0.5at^2 to find The distance the ball SLIPS??
2. If i can't use that equation, then How can i find the distance the ball slips?
3. In finding W= delta Kt + delta Kr, Do I have to use final angular and forward speed that i found from previous calculation or Do i have to find them?

Thank you for your help.
 
Last edited:
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Anybody?? I really need help
 
Please heLP!
 
nobody?
 
Sorry... maybe it's just me but I can't really understand the problem as you've stated it. Is the axis of rotation of the ball supposed to be parallel to the table? (The way you wrote it, it sounds like the ball is spinning around a vertical axis)
 
diazona said:
Sorry... maybe it's just me but I can't really understand the problem as you've stated it. Is the axis of rotation of the ball supposed to be parallel to the table? (The way you wrote it, it sounds like the ball is spinning around a vertical axis)

Its a billiard ball rotating on the table. If you ever played pool before, you know that once you hit the ball its both rotating and slipping then it rolls without slipping
 

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