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## Homework Statement

A flywheel made of glass fibre has been developed by BP to store the kinetic energy of buses when they come to a bus stop. The maximum energy stored in the flywheel is equivalent to the energy lost by a 16,000 kg bus braking from 48 km when it comes to rest. The bulk of the flywheel’s mass is in its rim which moves at 1300 km when the flywheel rotates at the maximum angular velocity of 16,000 rev . After a typical stop of two minutes during which time the flywheel slows down, four fifths of its energy is still available to accelerate the vehicle.

From this data show that the flywheel has the following properties:

- Maximum kinetic energy = 1.42 MJ
*(2 marks)*

- Moment of Inertia = 1.01 kg
*(3 marks)*

- Radius = 0.215 m
*(2 marks)*

mass = 21.9 kg*Minimum**(3 marks)*

(Each section must be answered in the order given. You may not assume data from the following sections).

e) Determine also the

- Determine also the mean frictional torque causing the slowing down in the two minute stop.
*(6 marks)*

## Homework Equations

not really sure!!

## The Attempt at a Solution

I cant figure out how to do this as I don't know how to do it In this order?