kinetic energy of a rotating wheel?

[badman]

A simple wheel has the form of a solid cylinder of radius r with a mass m uniformly distributed throughout its volume. The wheel is pivoted on a stationary axle through the axis of the cylinder and rotates about the axle at a constant angular speed. The wheel rotates n full revolutions in a time interval .
Express your answer in terms of m, r , n ,t and, pi .

does anyone have any pointers for me?

i do know that this formula, 1/2mr^2 can help me, but i dont know how create the right equation using the other arts given to me.

[Nylex]

Rotational kinetic energy is given by

KE_{rot} = \frac{1}{2}I\omega^2.

Just write everything in terms of the variables you've been given.

[badman]

this is my answer so far, but im having a problem with the angular of velocity
1/2*m*r^2*((2*PI)/n*t)^2. can anyone point me in the right direction

[Nylex]

It should have \frac{1}{4} at the front, because you have \frac{1}{2}\frac{1}{2}mr^2.

In your angular velocity, your n should be in the numerator of the fraction.

[BobG]

this is my answer so far, but im having a problem with the angular of velocity
1/2*m*r^2*((2*PI)/n*t)^2. can anyone point me in the right direction
Two problems with your answer.

You're using moment of inertia for a ring, not a solid wheel of uniform density. Technically, moment of inertia is:

I = \int_0^m r^2 dm

Unless you have to solve the integrals, it's usually easier to look up the solution. Moment of inertia of several shapes are at Eric Weisstein's World of Physics (http://scienceworld.wolfram.com/physics/MomentofInertia.html) (you need to scroll down a little to see the formulas)

Your angular velocity is measured in radians per second. You were given n revolutions in t seconds. Convert the revolutions per second:

\frac{n_- revs}{t_- sec} * \frac{2 \pi_- rad}{1_- rev} = \omega