- #1
Westin
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Homework Statement
A string is wrapped around a disk of mass 2.1kg and radius 0.045m. Starting from rest, you pull the string with a constant force of 13N along a nearly frictionless surface. At the instant when the center of the disk has moved a distance 0.13m, your hand has moved a distance 0.34m.
At this instant, what is the speed of the center of mass of the disk?
vcm= 1.2687 m/s
At this instant, how much rotational kinetic energy does the disk have relative to its center of mass?
Krot= ?
I provided the image for a visual aid.
Homework Equations
Krot = F*d
KE = 1/2 m v^2[/B]
K= 1/2 Iw^2
The Attempt at a Solution
Krot = F*d
Krot = (13)(.34m) = 4.42m
This is assuming all force from hand exerts to rotational KE, not sure what I am doing wrong.
My other attempt was trying to use energy conservation mgh=Iω^2/2[/B]