ROTATIONAL MOTION

Why do internal torques sum to zero in a system of particles?

• Internal forces are too small
• Internal torques are random
• They are not calculated
• Because internal forces act in pairs along the line joining particles

What is the role of the origin in calculating angular momentum?

• It must be at the center of mass
• It has no role
• It eliminates internal forces
• It serves as the reference point for position vectors

How does extending arms while spinning affect rotational kinetic energy?

• It always increases
• It remains constant
• It becomes zero
• It may decrease or increase depending on work done, but angular momentum is conserved

What happens to the angular momentum of a system when external torque is absent?

• It gradually vanishes
• It doubles
• It reverses direction
• It stays constant

What is the key principle behind a skater spinning faster when pulling arms in?

• Conservation of mechanical energy
• Newton's first law
• Law of inertia
• Conservation of angular momentum