ROTATIONAL MOTION

Why is the expression L = I ω k̂ not valid for all rotating bodies?

• Because I is constant
• Because ω varies
• It assumes symmetry so that L_⊥ = 0, which is not true for asymmetric bodies
• Because k̂ is arbitrary

What is the effect of shifting the origin along the rotation axis on L_⊥?

• No effect at all
• It always increases
• It may change L_⊥ if the body is asymmetric
• It reverses direction

How does the axial angular momentum of a rigid body differ from that of a single particle?

• It is always smaller
• It is independent of mass
• For a rigid body, it is the sum of all individual m_i r_i² ω terms
• It cannot be calculated

Why is the total L_⊥ zero for a uniform disk rotating about its central perpendicular axis?

• Because it doesn’t rotate
• Because mass is zero
• Due to symmetric cancellation of opposite particle contributions
• Because ω is infinite

What is the direction of the angular momentum vector for a particle moving clockwise in a horizontal circle when viewed from above?

• Upward
• Radially outward
• Tangential
• Downward (negative z-direction)