Torque

Overview

  • Rotational or twisting force (τ,"tau")
  • The product of force, distance, and the angle between force and lever arm
    • τ = F · d · sinθ
  • In the applications we will discuss today, the force and lever arm will be perpendicular
    • ∴ θ = 90 and sin90 = 1
  • so we get
    • τ = F · d
  • Given a fixed forque,
    • Larger distance → less force
    • Smaller distance → more force

In Levers

  • Key principle in levers (fulcrum, load, force)
    • First class: Crowbar
      • fulcrum between load and force
    • Second class: Wheelbarrow
      • load between fulcrum and force
    • Third class: Tweezers
      • force between fulcrum and load
  • You can add and subtract torques when multiple forces are acting about the same pivot point (eq. raising or lowering a wheelbarrow)
  • When the system is static (wheelbarrow is not being raised or lowered, such as while you are moving it from point A to B), torques are equal
  • The amount of load you can lift is dependant on the ratio of d1d2
    • τ1 = τ2
    • F1 · d1 = F2 · d2
    • F2 = d1d2 · F1