# Rotational kinetic energy of a wheel

## Homework Statement

I have a wheel with a diameter of 1.4m and the radius of gyration is 0.42m. The wheel has a mass of 13kg. Calculate maximum rotational kinetic energy.

## The Attempt at a Solution

From this all i can do is calculate the moment of inertia which is the mass (x) radius of gyration squared which gives me 2.29kg/m squared.
As far as i am aware i need the angular velocity to calculate the kinetic energy but i have no velocity figures. Any help is much appreciated

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Doc Al
Mentor
As far as i am aware i need the angular velocity to calculate the kinetic energy but i have no velocity figures.
Without more information, there's not much you can do. Did you present the full problem exactly as given, word for word?

You have to know how many turns it took so you can use: $$\frac{1}{2}J_{\Delta}\omega^{2}=M_{\Delta}*\Delta\theta$$ to calculate the maximal angular speed.

Then you can just plug it in and find your answer .

Ps: JΔ of a wheel : $$J_{\Delta}=M*R^{2}$$

yes that is all the information that is in the question. I have previously calculated a maximum linear velocity which i now assume is what i have to use to answer the question even though it makes no reference to it. Many thanks for your replies.

Doc Al
Mentor
yes that is all the information that is in the question. I have previously calculated a maximum linear velocity
So there are other parts to this problem? Post the entire problem, start to finish.