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I have hard time understanding the rotational inertia .

A string is wrapped around a cylindar spool of radius 1cm. The axis of the spool is fixed. A length of string of .8 m is pulled off in 1.5 s at a constant tension of 20N.

What is the rotational inertia of the spool?

Can I have some help with this problem?

I don't know how to start. The only definition of rotational inertia I have is I=mR^{2}!

Thank you

B.

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# Rotational inertia

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