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ljucf
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Homework Statement
A disk of radius 0.41 m and moment of inertia 2.8 kg·m2 is mounted on a nearly frictionless axle. A string is wrapped tightly around the disk, and you pull on the string with a constant force of 52 N.
What is the magnitude of the torque?
torque = 21.32 N·m
After a short time the disk has reached an angular speed of 4 radians/s, rotating clockwise. What is the angular speed 0.63 seconds later?
angular speed = ? radians/s
Homework Equations
torque = RFT
Rotational angular momentum = (MR2/2)ω
The Attempt at a Solution
The new angular momentum is the old angular momentum plus the angular impulse, torque times time interval.
(2.8/2)4 + (21.32)(.63) = 19.03 radians/s
However, this answers is wrong, and I can't figure out what I am doing wrong.