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Angular velocity-please help

  • #1

Homework Statement


a small puck of mass .5kg is executing Uniform constant motion on a friction free horizontal table. The angular frequency of the puck is 10 sec-1 (counter clockwise) and the radius of the circular motion is .8m. the radius stays fixed as the student holds the string in place. he now pulls the string down .5 m and holds it again in place. what work did he do?


Homework Equations



KE(original)+ W = KE (final)
inertia of hockey puck on string = mr2
w = angular velocity
I = inertia

The Attempt at a Solution


KE(original)+ W = KE (final)
.5(I)w2 +W = KE final
.5 (.5)(.8)2(102) + W = KE final

now i have a problem solving for kinetic energy final...
KE final = .5(.5)(.5)2(102)(w2)
I cant figure out what w (angular velocity) is...
please help!!!
 

Answers and Replies

  • #2
ideasrule
Homework Helper
2,266
0
Have you tried using the conservation of angular momentum?
 

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