A solid disk, spinning counter-clockwise, has a mass of $7 k g$ $7 kg$ and a radius of $8 m$ $8 m$ . If a point on the edge of the disk is moving at $14 \frac{m}{s}$ $14 m/s$ in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?

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Answer 1 · 2016-12-01T06:00:56

The angular velocity is $= 1.75 H z$ $=1.75 Hz$
The angular momentum is $= 686 k g m s^{- 1}$ $=686 kgms^(-1)$

The angular velocity is $ω = \frac{v}{r}$ $omega= v/ r$

velocity $= v = 14 m s^{- 1}$ $=v=14ms^(-1)$

radius $= r = 8 m$ $=r=8 m$

$ω = \frac{v}{r} = \frac{14}{8} = \frac{7}{4} H z$ $omega=v/r=14/8=7/4 Hz$

The angular momentum is $L = I ω$ $L=Iomega$

For a solid disc, $I = m r^{2}$ $I=mr^2$

$I = 7 \cdot 8^{2} = 392 k g m^{2}$ $I=7*8^2=392 kgm^2$

So, the angular momentum is

$L = 392 \cdot \frac{7}{4} = 686 k g m s^{- 1}$ $L=392*7/4=686 kgms^(-1)$

A solid disk, spinning counter-clockwise, has a mass of 7kg7 kg and a radius of 8m8 m. If a point on the edge of the disk is moving at 14ms14 m/s in the direction perpendicular to the disk's radius, what is the disk's angular momentum and velocity?