Rotational Dynamics, Energy and Momentum

Torque is the rotational analog of which of the following quantities?

• kinetic energy

• linear momentum

• acceleration

• force

Two wheels are fixed to each other and are free to rotate about a frictionless axis through their concentric centers. Four forces are exerted tangentially to the wheels. The magnitude of the net torque is _____

• zero

• FR

• 2 FR

• 4 FR

Tags

NGSS.HS-PS2-1

If the 6.0 kg mass is 4.0 m away from the pivot, how far away is the 10.0 kg mass if the system is not rotating?

• 0.42 m

• 2.4 m

• 4.8 m

• 6.3 m

The string supporting the 10 kg mass is cut. What is the net torque on the system?

• 60 N-m

• 120 N-m

• 240 N-m

• 480 N-m

Which of the following must be true for the below system of two concentric massless pulleys and two masses to be at equilibrium?

• m₁ = m₂

• m₁R₁ = m₂R₂

• m₁R₂ = m₂R₁

• m₁R₁² = m₂R₂²

Tags

NGSS.HS-PS2-1

A force, F, is applied to a doorknob and a second force, 2F is applied to the same door at its midpoint. Both forces are perpendicular to the door plane. Which of the following is the correct ratio between the torque of the first force and the torque of the second force?

• 2:1

• 1:2

• 4:1

• 1:1

In translational motion, mass is a measure of an object’s acceleration in response to a force. What is the rotational analog of mass?

• torque

• moment of inertia

• angular acceleration

• angular momentum

When a solid object rotates with a constant angular acceleration, which of the following is true?

• All points on the object rotate with the same centripetal acceleration.

• The net torque applied to the object must be zero.

• The net torque applied to the object must be a constant.

• All points on the object rotate with the same tangential acceleration.

In the diagram, two boxes with masses, 3 kg and 9 kg are attached to the ends of a 1 m long lever. At which of the following points should the lever be placed on a fulcrum in order to keep the lever at equilibrium?

• A or E

• B

• C

• D

Tags

NGSS.MS-PS2-4

Two uniform disks have the same radius but different masses: disk 1 has a mass M, disk 2 has a mass 2M. What is the ratio of the moment of inertia of the first disk to the second disk?

• 1:4

• 1:2

• 2:1

• 4:1