Centre of Gravity

Centre of Gravity

Definition

• The Centre of Gravity of an object is the point where its weight can be considered to act.
• In essence, it is the point where the whole weight of an object or shape seems to be concentrated.

Factors Affecting the Position of the Centre of Gravity

• The Centre of Gravity does not necessarily need to be within the physical confines of an object.
• Shapes which are uniform, such as regular squares, circles, will have their Centre of Gravity in the geometric middle.
• For irregular objects and shapes, the Centre of Gravity is found by experiment, often using a plumb line.

Centre of Gravity and Stability

• The stability of an object depends on the position of the Centre of Gravity and the area of support (base) of the object.
• An object is more stable if its Centre of Gravity is closer to the ground, and over its base.
• Objects with a low Centre of Gravity and a wide base area are the most stable.

Effect of Changing the Centre of Gravity

• If the Centre of Gravity of an object is altered (such as by changing the object’s shape, orientation or distribution of mass) the stability of the object will change.
• If the Centre of Gravity moves outside the base area, the object will topple.

Practical Applications of Understanding the Centre of Gravity

• Understanding the Centre of Gravity is vital in many areas of everyday life and engineering, for example designing stable structures and vehicles.
• Sportspeople and performers also utilise the principles of Centre of Gravity to achieve balance and control in their movements.