A spinning disk of radius 0.50 meters and mass 5.0 kg rotates clockwise at a rat

Question

A spinning disk of radius 0.50 meters and mass 5.0 kg rotates clockwise at a rate of 3 revolutions per second. A second disk and mass 4.5 kg) rotates (radius 0.25 meters 7. a. a. A 3 the other direction at the same rate. If the second onto the first disk so that their centers disk dropped of the two disks align find the rate of rotation and direction of the two disks together (Moment of inertia for a disk is 1/2 m r^2). If instead (moment of inertia = mr^2) with the same radius he second disk were a hoop two together? Explain your and mass, how would this affect the rotation of the response.

Explanation / Answer

7.(A) I1 = m r^2 /2 = 5 x 0.50^2 /2 = 0.625 kg m^2

w1 = 3 rev/s ( clockwise)

I2 = 4.5 x 0.25^2 /2 = 0.14 kg m^2

w2 = -3 rev/s

Applying angular momentum conservation,

(0.625 x 3) + (0.14 x -3) = (0.625 + 0.14) w

w = 1.90 rev/s

rate of rotation = 1.90 rev/s
direction- clockwise

(B) now I2 = 4.5 x 0.25^2 = 0.28 kg m^2

now applying angular momentum conservation,

(0.625 x 3) + (0.28 x -3) = (0.625 + 0.28) w

w = 1.14 rev/s

now rate of rotation is 1.14 revoutions per second and in clockwise direction.

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