ROTATIONAL MOTION Quiz

• When net external force is zero
• When velocity is constant
• When acceleration is zero
• When net external torque acting on the system is zero

• Same as angular momentum
• Downward
• Along the string
• Perpendicular to both the angular momentum vector and the gravitational force

• r + p
• r × p (as scalar)
• r / p
• Product of magnitude of position vector, linear momentum, and sine of angle between them

• They increase the total angular momentum
• They decrease it to zero
• They randomize its direction
• Internal torques cancel out and do not affect total angular momentum

• Because angular momentum cancels gravity
• Because the rim becomes weightless
• Because tension increases
• Because the torque leads to precession, not toppling