A solid cylinder of mass 20 kg rotates about its axis with angular speed 100 rad/s. The radius of the cylinder is 0.25 m. What is the kinetic energy associated with the rotation of the cylinder ? What is the magnitude of angular momentum of the cylinder about its axis ?

Explanation

Given: M=20kg, `omega=100"rad"s^(-1), R=0.25m`
M.I of the cylinder about its own axis,
`I=1/2MR^(2)=1/2xx20xx(.25)^(2)`
`=10xx0.0625=.625kgm^(2)`
Rotational K.E. `I=1/2 I omega^(2)`
`=1/2 xx0.625xx(100)^(2)`
`=0.3125xx10^(4)=3125J`
Angular momentum,
`L=I omega=0.625xx100`
`=62.5 kg m^(2)s^(-1)`