What is torque?
You may have heard of torque wrenches.  This tool takes your force, and applies it about an axis.
Simply then, a torque is a force applied about an axis.
Since torque is a force, its unit must be the Newton.

The amount of torque depends on three things...

  • distance from applied force to the axis of rotation (a longer handled wrench gives more torque)
  • the strength of the applied force
  • the angle you apply your force at (you get the most out of opening a door when you push at 90°)

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    The formula for finding a torque, given the above three variables is t = rFsinq.where q is measured in degrees from a line drawn from the axis to the applied force.

    Let's consider the example of opening a door...

  • if you push near the hinge, it is REALLY HARD to open because "r" is a small number
  • if you grab the knob and push more left or right rather than forward, it is REALLY HARD to open because as qdeviates from 90°, sinq gets smaller


    • What torque is produced by a wrench when a force of 100N is applied at a distance of .4m perpendicular to the wrench handle?
    t = rFsinq = (.4)(100)(sin90) = 40N

    What if the force is applied at an angle of 30 degrees away from the wrench handle?
    t = rFsinq = (.4)(100)(sin30) = 20N