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## Homework Statement

A bicycle has wheels of radius 0.29 m. Each wheel has a rotational inertia of 0.091 kg·m^2 about its axle. The total mass of the bicycle including the wheels and the rider is 79 kg. When coasting at constant speed, what fraction of the total kinetic energy of the bicycle (including rider) is the rotational kinetic energy of the wheels?

## Homework Equations

translational KE = 1/2 mv^2

rotational KE = 1/2 I (omega)^2 = 1/2 I (v/r)^2

rotational KE / total KE

= (I/r^2) / (I/r^2 + m)

## The Attempt at a Solution

Moment of inertia (I) is given: 0.091 kg·m^2

Radius of the wheel is .29 meters

Mass is 79kg

so:

rotational KE / total KE

= (I/r^2) / (I/r^2 + m)

=(0.091kg·m^2/0.29^2m) / (0.091kg·m^2/0.29^2m + 79kg)

=.0135 which is not the right answer.

Anyone know where I messed up?