ROTATIONAL MOTION

What is the meaning of dL/dt = 0 in angular momentum conservation?

• The system is at rest
• Torque is infinite
• The total angular momentum does not change with time
• Angular velocity is zero

What is the basis for τ = τ_ext in many physical systems?

• External forces dominate
• Internal forces are zero
• Internal forces cancel in torque due to being central
• The system is in equilibrium

How does the angular momentum of a single particle moving at constant velocity behave?

• It increases with time
• It decreases to zero
• It changes direction periodically
• It remains constant about any fixed point

What determines the direction of the torque vector?

• Direction of r only
• Direction of F only
• Left-hand rule
• The right-hand rule applied to r × F

What does the conservation of Lx, Ly, Lz imply about symmetry?

• It implies time symmetry
• It implies translational symmetry
• It implies charge symmetry
• Space is symmetric under rotation about those axes