Question

Fig. 1.42 shows three pieces of card board of uniform
thickness cut into three different shapes. On each
diagram draw two lines to indicate the position of the
centre of gravity G.

Answer 1

To Do :-

• On each of the given diagrams draw lines to indicate position of Centre of Gravity.

SolutioN :-

$\large\underline\red{\sf Breif \ Introduction :- }$

When we consider a rigid body , it has a number of particles and these particles are attracted towards the Earth due to gravity . Let the forces acting on the body be $\sf F_1 , F_2 , F_3 . . . .$ . These forces acts downwards in parallel lines. this forces can be replaced by a single resultant force whose effect is same as that of the combination . This resultant force acts at a particular point and this point can be assumed as the point where the whole weight of the body acts. This point is called Centre of Gravity .

$\to\sf\red{ \overrightarrow{W} = \overrightarrow{F_1}+ \overrightarrow{F_2}+\overrightarrow{F_3}+ \cdots }$

$\rule{200}2$

$\purple{\dashrightarrow}$ For finding the centre of gravity draw diagonals in case of square/rectangle . The point where the diagonals Intersect is the COG .

$\purple{\dashrightarrow}$ For finding the centre of gravity in case of triangle , draw medians from vertices to the opposite sides . The point where the medians intersect is the COG .

$\purple{\dashrightarrow}$ The centre of gravity of the circle will be the centre of the circle .

Now refer to the attachment .