AP Torque and Angular Momentum

A person sits on a freely spinning lab stool that has no friction in its axle. When this person extends her arms,

• her moment of inertia increases and her angular speed decreases.
• her moment of inertia decreases and her angular speed increases.
• her moment of inertia increases and her angular speed increases.
• her moment of inertia increases and her angular speed remains the same.

A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it is true to say that

• the moment of inertia of the system increases and the angular speed increases.
• the moment of inertia of the system decreases and the angular speed remains the same.
• the moment of inertia of the system decreases and the angular speed decreases.
• the moment of inertia of the system decreases and the angular speed increases.

A uniform solid cylinder with a radius of 10 cm and a mass of 3.0 kg is rotating about its center with an angular speed of 33.4 rpm. What is its kinetic energy?

• 0.092 J
• 17 J
• 1.1 J
• 0.18 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-3

In order to do a lot of flips an Olympic diver would want:

• A high rotational inertia
• A low rotational inertia
• A low linear acceleration
• A low angular velocity

Which has greater angular speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?

• The inside horse
• The outside horse
• Neither - they both have the same angular speed

Two children, Ahmed and Saleh, ride on a merry-go-round. Ahmed is at a greater distance from the axis of rotation than Saleh. Which of the following are true statements? 

• Saleh and Ahmed have the same tangential speed.
• Ahmed has a greater tangential speed than Saleh.
• Saleh has a greater angular speed than Ahmed.
• Saleh has a smaller angular speed than Ahmed.

In the absence of external forces a rotating ball of hot gas cools and contracts, its angular momentum...

• decreases
• remains essentially the same
• increases

Tags

NGSS.HS-PS2-2

In the absence of external forces a rotating ball of hot gas cools and contracts, its rate of rotation...

• decreases
• remains essentially the same
• increases

Tags

NGSS.HS-PS3-4

A man in a gym is holding an 8.0-kg weight at arm's length, a distance of 0.55 m from his shoulder joint. What is the torque about his shoulder joint due to the weight if his arm is horizontal?

• 43 N ∙ m
• 0 N ∙ m
• 15 N ∙ m
• 0.24 N ∙ m

What does the rotational inertia describe? 

• The average position of mass in an extended object.
• How the mass of an object is distributed 
• How a force can rotate an object.
• The tendency of an object to move in a straight line.