Understand the condition for rotational equilibrium: Στ = 0
Calculate torques from multiple forces about a pivot
Predict which way a lever will tilt
Key Equations
\( \tau = r \times F = rF\sin\theta \)
\( \sum \tau = 0 \;\text{(equilibrium)} \)
\( m_1 d_1 = m_2 d_2 \;\text{(balanced lever)} \)
Why It Matters
Torque explains how wrenches work, why doors have handles far from hinges, and how seesaws balance. Understanding rotational equilibrium is essential for engineering bridges, cranes, and the human body's musculoskeletal system.