A solid disk, spinning counter-clockwise, has a mass of 2 kg2kg and a radius of 7/4 m74m. If a point on the edge of the disk is moving at 7/9 m/s79ms in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

1 Answer
Nov 11, 2016

The angular momentum is =49/36 kgm^2s^(-1)=4936kgm2s1
The angular velocity is =4/9 Hz=49Hz

Explanation:

The angular velocity is omega=v/rω=vr

Here v=7/9 ms^(-1)v=79ms1 and r=7/4 mr=74m

therefore omega = 7/9*4/7=4/9 Hzω=7947=49Hz

The angular momentum is L=I*omegaL=Iω
Where II is the moment of inertia
For a solid disc I=(mr^2)/2=2*(7/4)^2/2=49/16 kgm^2I=mr22=2(74)22=4916kgm2

So, the angular momentum is 49/16*4/9=49/36 kgm^2s^(-1)491649=4936kgm2s1