Question on Rotational Dynamics

[alamin]

1.A uniform Disc of Radius R is rotating in its own plane with angular velocity w when it is placed flat on a rough table. If u the coefficient of sliding friction is independent of velocity show that the time taken for the disc to come to rest is
(3RW)/(4ug). How does the kinetic energy of rotation of the disc vary with time?

[stunner5000pt]

ok please show us what work you have done. we arent gonna solve (although we can) your problems for you
also for your problems remember that
\Delta K + \Delta U = W_{friction}
where K represnets kinetic energy
U represnts potential energy
and W represents work
and delta is the change

[Harmony]

May I know what is the formula to calculate work done by frcition? Displacement is given in the case, but the friction force is not.

[stunner5000pt]

work done is F d cos(angle)
if angular then d = (angular displacement)

[Psi-String]

work done is F d cos(angle)
if angular then d = (angular displacement)
I thought the work done by the friction force is \int \vec{\tau} \cdot d\vec{\theta}?

[Tom Mattson]

Psi-String,

We appreciate that you are willing to assist, but please do not offer complete solutions to homework questions.

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