Question

Trucks can be run on energy stored in a rotating flywheel, with an electric motor getting the flywheel up to its top speed of 689 rad/s. One such flywheel is a solid, uniform cylinder with a mass of 507 kg and a radius of 1.2 m that rotates about its central axis. What is the kinetic energy of the flywheel after charging

Answer 1

k = 86,646,076.92 J

Step-by-step explanation:

We know that:

K =
`(1)/(2)IW^2`

where K is the kinetic energy, I is the moment of inertia and W is the angular velocity.

First we have to find the I with the equation:

I =
`(1)/(2)MR^2`

where M is the mass and R the radius of the cylinder.

so:

I =
`(1)/(2)(507 kg)(1.2m)^2`

I = 365.04 kg*m^2

Now we replace all the data in the first equation as:

K =
`(1)/(2)IW^2`

K =
`(1)/(2)(365.04)(689)^2`

k = 86,646,076.92 J