AP® Physics 1 & 2

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Moderate

Angular Momentum New Radius

APPH12-85U09O

A flat disk with a radius of $0.50 \text{ m}$ and a mass of $1.0 \text{ kg}$ is rotating about an axis of rotation perpendicular to the disk and through the center of mass at an angular velocity of $5.0 \text{ rad/s}$.

Suddenly the angular velocity changes to $3.0 \text{ rad/s}$ with no accompanying change in mass.

If there is no net torque on the disk, which of the following best approximates the new radius of the disk?

A

$0.65\text{ m}$

B

$0.42\text{ m}$

C

$1.88\text{ m}$

D

$0.83\text{ m}$