Moments

• Define a moment

  The turning effect of a force about a pivot
• What is the equation for calculating moments?

  moment= force x perpendicular distance from the pivot

  M= Fd
• What is the principle of moments?

  The total clockwise moment is equal to the total anticlockwise moment about a pivot
• The principle of moments describes the equilibrium condition in a balanced system
• Define equilibrium in terms of moments

  Equilibrium is a state in which an object remains unchanged in its motion or rotation, with balanced forces and moments acting upon it
• Describe an experiment to demonstrate that there is no resultant moment on an object in equilibrium

  1. Use a meter ruler as a beam
  2. Suspend it via two Newton metres, one on each side, that each hang from a clamp stand
  3. Force 1 is the reading given on the left side Newton meter and Force 4 is the reading given on the right
  4. Create a loop of string, tie a tight knot and slide the ruler through it
  5. Force 3 will be the weight of a mass hook with 10N weight suspended from this string
  6. Force 2 is the weight of the beam
• Define the resultant moment

  The net turning effect produced by the combination of all forces acting on an object, determining its rotational motion
• Define the centre of gravity

  The point at which the weight of the object can be considered to act
• Describe an experiment to determine the position of the centre of gravity of an irregularly shaped plane lamina

  The plane laminar is suspended from a pivot and allowed to settle

  A lead weight is then held next to the pivot and a pencil is used to draw a vertical line from the pivot

  The process is then repeated, suspending the shape from two different points

  The centre of gravity is located at the point where all three lines cross
• Define stability

  An object's ability to maintain its equilibrium position, where its centre of gravity lies above its base
• An object is stable if its centre of gravity lies above its base, ensuring balance and preventing it from tipping over
• How does the width of the base affect an object's stability?

  A wider base lowers the centre of gravity, increasing stability, while a narrower base raises it, decreasing stability
• What factors influence an object's stability

  The position of its centre or gravity and the width of its base
• State the condition required for an object to be stable

  When its centre or gravity is positioned above its base, ensuring equilibrium and resistance to tipping
• How does the position of the centre of gravity affect stability?

  It determines whether an object will remain balanced or topple over when disturbed