ROTATIONAL MOTION

How does the conservation of angular momentum apply to a freely rotating rigid body in space?

• It slows down due to internal friction
• It requires continuous torque
• Its angular momentum remains constant if no external torque acts
• It loses energy and stops

What is the consequence of having zero net external torque on a system?

• The system stops rotating
• The angular velocity becomes zero
• The total angular momentum is conserved
• The moment of inertia increases

In the expression τ = Σ r_i × F_i, what type of forces does F_i include?

• Only gravitational forces
• Only external forces
• Only internal forces
• Both external and internal forces

What is the relationship between τ_ext and the time derivative of L?

• τ_ext = L
• τ_ext = d²L/dt²
• τ_ext = 0
• τ_ext = dL/dt

Why is the assumption of central internal forces important in mechanics?

• It increases kinetic energy
• It causes expansion of the system
• It ensures that internal torques cancel out
• It simplifies mass calculation