Center of gravity | Centroid

Definition of center of gravity:

The center of gravity is the point that shows the average location of the weight of an object. The point through which the whole mass of body acts, irrespective of the position of the body is known as a center of gravity OR centroid. 

The plain geometrical figures such as rectangle, triangle, circle all have only areas not mass. The center of an area of all such figures is known as a center of gravity of the area of the body. Every object has one and only one centroid. 

Types of figure and its center of gravity:

• The center of gravity of a uniform rod is at a middle point of the rod. 
• The center of gravity of a rectangle or parallelogram lies at a point where its diagonal intersects. 
• The center of gravity of a triangle lies at a point where the three medians of the triangle intersect.  

For a general shaped object, there is a simple mechanical way to determine the center of gravity which is the following below. 

• The point at which the object balanced if we just balance the object using a string or an edge is the center of gravity. For example: Balancing a pencil on your finger. 
• Another way is a two-step method. Step1, you hang the object from any point and you drop a weighted string from the same point then draw a line on the object along the string. Step2, repeat the same process from anothe3r point on the object then again draw a line on the object which intersects. The center of gravity is the point where the line intersects. This way works well for an irregular shaped object which is hard to balance.