AP Rotation Test Review

A long rod is suspended by a frictionless bearing near its top. A lump of clay is projected from the right, collides with the block and sticks to it. Which one of the following statements is correct about the clay and rod system for this collision?

• The mechanical energy, linear momentum and angular momentum remain constant.

• The linear momentum and the angular momentum remain constant but the mechanical energy changes.

• Only the angular momentum remains constant.

• None of the quantities of mechanical energy, linear momentum, or angular momentum remain constant.

Tags

NGSS.HS-PS2-2

When a high diver wants to turn a flip in midair, she will often draw her legs up against her chest.  Why does this make her rotate faster?

• This increases the torque produced by her legs thus increasing her angular acceleration.
• This decreases her moment of inertia thus increasing her angular speed.
• This decreases her angular momentum thus increasing her angular kinetic energy.

A box and a hollow sphere are both released from rest at the top of the same hill.  The box slides down the hill unimpeded while the ball rolls down.  At the bottom, which has the largest linear velocity?

• The ball.
• The box.
• They both have the same linear velocity.
• It depends on the mass of each.

A disk initially rotating counterclockwise (CCW) at a certain constant angular speed is suddenly being pulled on by two strings T₁ and T₂, where T₂ > T_1. What is going to happen next?

• The disk will continued rotating CCW at the constant angular speed.

• The disk will continued rotating CCW but it will speed up

• The disk will slow down and start rotating CW

• The disk will eventually stop rotating

Tags

NGSS.HS-PS2-1

Stars originate as large bodies of slowly rotating gas.  Because of gravity, these clumps of gas slowly decrease in size.  What happens to the angular speed of the start as it shrinks?

• It rotates faster.
• It rotates slower.
• It starts to accelerate in the forward direction.
• The rotation rate stays the same.

A figure skater is initially rotating with his arms stretched out at an angular speed ω₀ and with initial inertia I₀. If after pulling in his arms his inertia is only 1/3 I₀, how has his angular speed changed?

• It's now 3 times smaller

• It's now 3 times larger

• It stays the same

A careful inspection of the boy playing solitary seesaw indicated the mass of the boy is....

• Greater than the mass of the seesaw.
• Less than the mass of the seesaw.
• Equal to or very nearly the mass of the seesaw.
• Not enough information is given.

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

What is the center of mass ?

• it is a single point at which the object can balance.
• The mass is distributed equally around it.
• the center of gravity of the object
• All of the above