AP Physics Rotational Kinematics and Torque

When a car goes around a corner at 20 mph, why do we say it  accelerates?

• The car is accelerating because of the velocity is constant

• The car accelerates because it's going 20 mph

• Cars always accelerate when they are in motion

• The car is accelerating because it's changing direction

A fan blade, initially at rest, rotates with a constant acceleration of 0.025 rad/s². What is the time interval required for it to reach a 4.2 rad displacement after starting from rest   

• 1.8 s

• 2.0 s

• 16 s

• 18 s

A 0.12-m-radius grinding wheel takes 5.5 s to speed up from 2.0 rad/s to 11.0 rad/s. What is the wheel's average angular acceleration?

• 9.6 rad/s²

• 4.8 rad/s²

• 3.1 rad/s²

• 1.6 rad/s²

A wrench is used to tighten a nut. A 15N perpendicular force is applied 50cm away from the axis of rotation, and moves a distance of 10 cm as it turns. What is the torque applied to the wrench?

• 7.5 Nm

• 1.5 Nm

• 750 Nm

• 150 Nm

A force in a circular direction

• Reciprocating

• Torque

• Speed

• Oscillating

What is torque?

• Torque is a measure of the linear force applied to an object.

• Torque is a unit of temperature measurement.

• Torque is a type of musical instrument.

• Torque is a measure of the force that tries to rotate around an axis

Harry Potter waved his .23 m wand with .069 Nm of torque. How much force did Harry apply to rotate his wand?

• .4

• .5

• .3

• .16

If the torque required to loosen a nut on the wheel of a car has a magnitude of 60.0 Nm, what minimum perpendicular force must be exerted by a mechanic at the end of a 45.0 cm wrench to loosen the nut?

• 2700 N

•  133 N

• 27 N

• 1.3 N

Which requires more muscle strength (pull by the muscle) to lift a 25 pound dumbbell?

• An arm with a longer forearm

• An arm with a shorter forearm

• The length doesn't matter

A gear spins at a rate of 400 revolutions/minute. Which choice is closest to its angular speed in radians/second?

• 6.67 rad/s

• 2500 rad/s

• 41.9 rad/s

• 20.9 rad/s