rotational inertia

Discussion in 'Physics' started by braddy, Oct 30, 2005.

  1. braddy

    Thread Starter Well-Known Member

    Dec 29, 2004

    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