Centre of Gravity of an Irregular Shaped Body:

Centre of Gravity of an Irregular Shaped Body:

Plumb line is a small metallic conical piece attached to a string. When the plumb line is displaced, it always comes to rest in the vertical position. Two vertical forces act on it, (1) its weight (2) tension in the string. These forces act along the same vertical line. Thus vertical line passes through the centre of gravity of the plumb line. The centre of gravity of the plumb line is vertically below the point of suspension. This fact provides a simple method for finding experimentally the centre of gravity of irregular shaped bodies. This method is as under:

Drill three small holes near the edge of the plate whose centre of gravity is to be located. Suspend the plate from a nail fired horizontally in a wall using one of the holes, say A. When the plate is at rest, suspend a plumb line from the nail. Draw a line Aa on the plate along the plumb line. The centre of gravity lies somewhere on the line Aa.

Repeat the above procedure with hole B on the nail. Again the centre of gravity must lie somewhere on the line Bb. The only point common to the lines Aa and Bb is G, therefore this point must be the centre of gravity. If the plate is suspended using third hole C, the line Cc will also pass through the point G.