Moment of Inertia and Angular Speed

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To determine the angular speed of a top with a moment of inertia of 4.40 x 10^-4 kgm², initially at rest, a string is pulled with a constant tension of 5.19 N for 80.0 cm. The work done by the string is calculated, leading to the understanding that this work results in a change in kinetic energy. The relevant equation is delta K = 0.5I(final angular velocity² - initial angular velocity²). By applying these concepts, the angular speed can be derived from the work-energy principle.
TrippingBilly
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A top has a moment of inertia of 4.40 10-4 kgm2 and is initially at rest. It is free to rotate about the stationary axis AA'. A string, wrapped around a peg along the axis of the top, is pulled in such a manner as to maintain a constant tension of 5.19 N. If the string does not slip while it is unwound from the peg, what is the angular speed of the top after 80.0 cm of string has been pulled off the peg? (The picture of the top shows it rotating clockwise about a vertical axis A)

This question has me stumped. If someone could point me in the right direction with regards to a concept I need to know or something I would appreciate it.
 
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Hint: How much work is done by the string?
 
At first I didn't see where you were going, but then I realized that work = change in energy. Which enabled me to use that wonderful equation
delta K = .5I(final angular velocity^2 - initial angular velocity^2). Thanks for the hint!
 

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