Centre of gravity

• what is the centre of gravity?

  The centre of gravity of an object is is the location where an object's weight appears to act. 

  For uniform, regular shapes, like a square, this will be in the centre.

  For irregular shaped objects or those with uneven densities, it will be off centre. 

  
• How do you find the centre of gravity for an irregularly shaped object?

  1. Suspend the irregularly shaped object from a clamp stand.
  2. Attach a plumb line to the clamp stand.
  3. Mark the plumb line on the object using a pencil.
  4. Remove the object and suspend from a different point. Repeat steps 2 and 3.
  5. Repeat step 4 until a minimum of three lines have been drawn. 
  6. The centre of gravity is located where all lines cross.

  
• How does the centre of gravity affects stability?

  An object's stability depends on its centre of gravity. By considering where the centre of gravity is located and how the weight acts on the object, we can determine if the object will be stable or unstable when tilted (i.e. whether or not it will fall over).

  An objects weight always acts vertically downwards from its centre of gravity.
• When and how is an object stable?

  If the weight acts within the base of an object, it is stable. Objects which have a wide base and a low centre of gravity are the most stable.

  
• What happens when an object is tilted?

  When an object is tilted, the weight moves towards the pivot point. 

  When released, the object will return to its original position due to a correcting moment provided by the weight.

  
• When is an object unstable and what happens when it is?


  If the object has been tilted so that the weight no longer acts within the base of the object, it is no longer stable. 

  When released, the object will topple over due to the toppling moment caused by the weight.