Homework Help: Flywheel in Trucks

1. Oct 26, 2007

BuBbLeS01

1. The problem statement, all variables and given/known data
Delivery trucks that operate by making use of energy stored in a rotating flywheel have been used in Europe. The trucks are charged by using an electric motor to get the flywheel up to its top speed of 960 rad/s. One such flywheel is a solid homogenous cylinder, rotating about its central axis, with a mass of 550 kg and a radius of 0.65 m. What is the kinetic energy of the flywheel after charging?

If the truck operates with an average power requirement of 9.3 kW, for how many minutes can it operate between charging?

2. Relevant equations
K = 1/2Iw^2
I = 1/2mr^2

3. The attempt at a solution
K = 1/2 * (.5 * 550 * .65^2) * 960^2 = 5.35 x 10^7
I a, getting a really huge number I wanted to make sure I am doing it right.

2. Oct 26, 2007

JFonseka

Well convert radians per second to metres per second.

Then K = 0.5 (m) (v)^2

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