Unit 5: Rotation

An ice skater spinning with arms extended pulls her arms in. What happens to her angular velocity?

A wheel completes 10 revolutions in 5 seconds. Its angular velocity is

A disk and a hoop of the same mass and radius roll down a frictionless incline from the same height. Which reaches the bottom first?

A figure skater pulls her arms inward during a spin, reducing her moment of inertia by half. Her angular velocity

The centripetal acceleration of an object moving at 10 m/s in a circle of radius 5 m is

A wheel of radius 0.5 m rotates at 10 rad/s. The linear speed of a point on its rim is

A spinning disk has angular momentum [math]. If its moment of inertia is halved while no external torque acts, its angular velocity becomes

A wheel accelerates uniformly from rest to 120 rad/s in 6 s. The number of revolutions it makes is

Airbags in cars reduce injuries by:

In which type of collision is kinetic energy conserved?

A 2 kg ball moving at 5 m/s collides head-on with a 3 kg ball at rest. They stick together. What is the final velocity?

The total momentum of an isolated system (no external forces):

A 0.2 kg ball moving at 10 m/s to the right bounces off a wall and returns at 8 m/s to the left. What is the magnitude of the change in momentum?

An object at rest explodes into two pieces. What can be said about their momenta?

On a Force vs. Time graph, the impulse on an object is represented by:

A 10 g bullet traveling at 400 m/s embeds in a 2 kg block. What is the velocity of the block-bullet system?

In an elastic collision:

A ball is thrown at a wall. Which scenario results in a greater impulse on the wall — the ball bouncing off or sticking?

If no external forces act on a system, the center of mass:

What is the angular velocity of the wheel?

Which point has the greatest tangential speed?

What is the angular acceleration of the wheel?

Which object has the greatest moment of inertia about its center?

What is the rotational kinetic energy of the disk?

What is the total kinetic energy of the rolling sphere?

What is the angular momentum of the disk?

What is the new angular velocity after the student pulls in her arms?

What is the centripetal acceleration of the object?

How many complete revolutions does the wheel make?

A solid disk and a hollow ring, both with the same mass and radius, roll down the same incline from rest. Which reaches the bottom first, and why?

A figure skater spinning with arms extended has a moment of inertia of 4.0 kg·m² and angular velocity of 2.0 rad/s. When she pulls her arms in, her moment of inertia becomes 1.6 kg·m². What is her new angular velocity?

A 0.5 kg ball on a 1.2 m string moves in a vertical circle. What minimum speed at the top of the circle keeps the string taut?