AP Physics - Rotational Dynamics

τ θ ω ⊥ ∝

Torque

  • Torque

    • Force that creates rotation

      • τ

    • If line of force passes through center of rotation, force will not create rotation

    • τ ∝ F

  • Lever Arm / Moment Arm

    • Perpendicular distance from pivot (axis of rotation) to line of force

    • r⊥ ∝ τ

  • A longer lever arm is very helpful in rotation object

Static Equilibrium

  • 1st Condition

    • ΣF = 0

  • 2nd Condition

    • ΣF = 0

Torque and Rotational Inertia

  • Knowing that F = ma, we see that τ = mr2a

  • As the angular acceleration is the same for the whole object, we can write:

    • Στ = (Σmr2) a

  • Moment of inertia => (cursive) L