ROTATIONAL MOTION

How does a diver control rotation speed during a dive?

• By changing body weight
• By pushing off water vapor
• By rotating limbs independently
• By changing body shape to alter moment of inertia

How does a circus acrobat increase their spin rate mid-air?

• By pushing against air
• By increasing body mass
• By using internal motors
• By pulling limbs close to reduce moment of inertia

Why does a person on a frictionless rotating chair slow down when they stretch their arms?

• Air resistance increases
• Friction increases
• Muscular force opposes motion
• Moment of inertia increases, decreasing angular speed to conserve angular momentum

What happens to angular momentum when no external torque acts on a system?

• It gradually decreases
• It increases
• It changes direction randomly
• It remains constant

Why do internal forces not contribute to net torque on a system?

• They are too weak
• They act at the center
• They do not produce rotation
• They act along the line joining particles and their torques cancel in pairs