The stability of an object depends on the . (Centre of gravity / Centre of mass)

A uniform metre scale is in equilibrium as shown in the diagram :

Calculate the weight of the metre scale.
Which of the following options is correct to keep the ruler in equilibrium when $40 \mathrm{gf}$ weight is shifted to $0 \mathrm{cm}$ mark?
$F$ is shifted towards $0 \mathrm{cm}$ or $F$ is shifted towards $100 \mathrm{cm}$.

The position of the centre of gravity of an object affects its stability. 

In general, increasing the size of the base (that is area) of support increases stability.