A solid cylinder of mass `20 kg` rotates about its axis with angular speed `100 s^(-1)`. 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

M=20 kg Angular speed, `w=100 rad s^(-1), R=0.25 m`
Moment of inertia of the cylinder about its axis
`=1//2 MR^(2)=1//2xx20(0.25)^(2) kg m^(2)=0.625 kg m^(2)`
Rotational kinetic energy,
`E_(r )=1//2 lw2=1//2xx0.625xx(100)^(2)J=3125 J`
Angular momentum, `L=l_(w)=0.625xx100 J_(s)=625.5 J_(s)`.