ROTATIONAL MOTION

When is a rigid body in rotational equilibrium?

• The total external force is zero
• The total external torque on the body is zero
• The linear momentum is zero
• The kinetic energy is constant

What condition must be met for a rigid body to be in translational equilibrium?

• The total external torque is zero
• The total external force on the body is zero
• The moment of inertia is zero
• The angular velocity is constant

A rigid body is in mechanical equilibrium if:

• It is in translational equilibrium only
• It is in rotational equilibrium only
• It is in both translational and rotational equilibrium
• Its center of mass remains stationary

How does conservation of angular momentum apply to celestial bodies?

• Causes gravitational collapse
• Stops planetary motion
• Makes planets spherical
• Explains stability of planetary orbits and rotational speeds

What distinguishes rotational from translational motion in rigid bodies?

• Mass of the body
• Speed of motion
• Temperature
• Presence of a fixed axis or point