A solid disk, spinning counter-clockwise, has a mass of 16 kg16kg and a radius of 3/7 m37m. If a point on the edge of the disk is moving at 7/5 m/s75ms in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Jan 30, 2018

The angular momentum is =4.81kgm^2s^-1=4.81kgm2s1 and the angular velocity is =3.27rads^-1=3.27rads1

Explanation:

The angular velocity is

omega=(Deltatheta)/(Deltat)

v=r*((Deltatheta)/(Deltat))=r omega

omega=v/r

where,

v=7/5ms^(-1)

r=3/7m

So,

The angular velocity is

omega=(7/5)/(3/7)=3.27rads^-1

The angular momentum is L=Iomega

where I is the moment of inertia

For a solid disc, I=(mr^2)/2

The mass is m= 16kg

So, I=16*(3/7)^2/2=1.47kgm^2

The angular momentum is

L=1.47*3.27=4.81kgm^2s^-1