Kinetic Energy of a flat uniform disk

[themilkman]

Homework Statement

A flat, uniform, disk, of radius 1.5 m and mass 10 kg, is rolling on its edge with a translational velocity of 12 m/s.
What is the kinetic energy of the disk?

Homework Equations

not sure which one but I'm guessing it's one of these two:
K = .5(I)(w)^2
K = .5(Icm)(w)^2 + .5(M)(v)^2cm

The Attempt at a Solution

I have absolutely no idea how to even start this problem, any help on what eqn to use and what I is would be extremely helpful

 

[mgb_phys]

For a rolling object - the total energy is the kinetic energy of the moving mass PLUS the rotational energy.

 

[thomate1]

.

I would first clarify the problem by asking for more information. Specifically, I would ask for the moment of inertia (I) of the disk, which is needed to calculate its kinetic energy. The moment of inertia depends on the shape and mass distribution of the object, so it cannot be determined without this information.

Once the moment of inertia is known, the first equation you listed (K = .5(I)(w)^2) can be used to calculate the kinetic energy of the disk. In this case, the angular velocity (w) can be calculated using the relation w = v/r, where v is the translational velocity and r is the radius of the disk.

Alternatively, the second equation (K = .5(Icm)(w)^2 + .5(M)(v)^2cm) can also be used. This equation takes into account both the rotational and translational kinetic energy of the disk, where Icm is the moment of inertia about the center of mass and vcm is the velocity of the center of mass.

In summary, to solve this problem, we need to know the moment of inertia of the disk and use one of the above equations to calculate its kinetic energy. Without this information, it is not possible to provide a specific answer.