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Rotational Motion Quiz


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1. An ice skater spins with an angular speed of 2.48 rev/s. She brings her arms in and her new angular speed is rev/s. By what factor did her rotational inertia change?

2. If a planet takes about h to rotate about its axis, what is the planet's angular speed in rad/s?

3. A wheel with a radius of m and rotating at 6.28 rev/s slows to 28.7 rev/s over a period over an interval of 3.00 s. What is the angular acceleration of the wheel in rev/s/s?

4. A solid disk (diameter = 20.0 cm) rolls along a horizontal surface so that its center proceeds to the right with a speed of m/s. What is the instantaneous speed (in m/s) of point B with respect to the ground?

A solid disk rolls with point B at the 9 o'clock position.

5. A force of N is applied to a doorknob at an angle of 76º to the door. The hinge is 78.8 cm from the doorknob. What is the torque (in N-m) on the door?

A force pulls on a doorknob at an angle to the door, toward the hinge.

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May The Force be with you.