Torque

1
Torque

• A turning force

2
Torque (T) a turning force

• Torque depends on the linear force applied and
  the distance from the fulcrum (pivot point)
• Eg pushing a door is harder from near the hinge
  than near the handle

3
Torque is a vector

• Because it is a turning force, the direction is
  given as clockwise or anticlockwise
• T Fd so the units are Nm

4
Common examples of torques are levers, seesaws
and bridges

• The best approach to finding total torque is to
  find the clockwise torques and balance against
  the anti clockwise ones

5
Force, Torque and Equilibrium

• When an object is at rest or moving uniformly it
  is said to be in equilibrium

6
Forces and Equilibrium

• 2 forces are in equilibrium if they are equal and
  opposite
• 3 forces are in equilibrium if their vector sum
  0 (a closed triangle)
• Any number of forces are in equilibrium if they
  form a closed vector diagram

7
A torque needs

• A name turning force or torque
• A pivot point fulcrum
• A size for the force and the perpendicular
  distance from the fulcrum
• A formula T Fd (units Nm)
• A direction clockwise or anticlockwise direction

8
Solving torque problems

• Draw a diagram
• Find and sum the clockwise Torques (Tc)
• Find and sum the anti-clockwise Torques (TA)
• Equilibrium exist if the TA Tc

9
To be in equilibrium

• The forces must be balanced
• The torques must be balanced!
• If the torques are unbalanced then there is a
  total force (also called net force) and
  acceleration happens. The system is not in
  equilibrium.