Question

g A flywheel consisting of a rotating steel disk with a radius of 0.50 m and a mass of 400 kg is rotating about its fixed axis by an electric motor. The axis of rotation of the disk passes through the center of mass of the disk, and the axis is also perpendicular to the disk. How much average power must the motor deliver to take the flywheel from rest to 2.0 revolution/second in 15 seconds

Answer 1

Average power will be equal to 6.66 watt

Step-by-step explanation:

We have given radius R = 0.5 m

Mass of disk m = 400 kg

Angular velocity
`\omega =2rad/sec`

Time is given t = 15 seconds

Moment of inertia of disk
`I=(1)/(2)mR^2`

`I=(1)/(2)* 400* 0.5^2=50kgm^2`

Rotational energy is equal to
`KE_(rotational)=(1)/(2)I\omega ^2`

`KE_(rotational)=(1)/(2)* 50* 2^2=100J`

Average power is equal to
`P=(energy)/(time)`

`P=(100)/(15)=6.66watt`

Average power will be equal to 6.66 watt