ROTATIONAL MOTION

How does Eq. (6.28b) differ from Eq. (6.17)?

• They are identical
• One applies to energy, the other to momentum
• One is rotational, the other is translational
• They differ in units only

What is the basis for τ_int = 0 in many systems?

• Conservation of energy
• First law of motion
• Newton’s third law and central force assumption
• Thermodynamic equilibrium

Can a system have zero external torque but non-zero internal torques?

• No, internal torques cannot exist
• Yes, but internal torques cancel each other
• Yes, and they add up
• No, only external torques matter

What is the unit of torque?

• Joule
• Watt
• Kilogram-meter
• Newton-meter (N·m)

How is the total torque separated into contributions?

• Into radial and tangential parts
• Into gravitational and electromagnetic
• Into external and internal torques
• Into static and dynamic