# rotational inertia

Joined Dec 29, 2004
83
Hi,

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[sup]2[/sup]!

Thank you

B.