In case of office chair model,it controls our weight on it's two legs.what are the forces responsible there?

i.e. here chair is inthe form of S shape in the sense it stands on two legs and a horizontal support, our whole weight is acting on it 's seat and gravitational force acts toward the ground so which force is acting opp to it in order to keep ourself stableIn case of office chair model,it controls our weight on it's two legs.what are the forces responsible there?
The force that an object exerts on the earth due to gravity... The earth exerts the same force back onto the object.





In the case of the chair:





Your weight + the chairs weight is exerted onto the floor due to gravity. The floor exerts this same force back onto the chair.





However since it has 2 legs, this total weight will be distributed onto the 2 legs. Remember only if you sit in the centre of the chair and if the 2 legs on symmetrical about ur weight will the force on the 2 legs be equal. when these forces are equal you are balanced(thats y u fall over if u lean to one side).





Lets take an eg:





Suppose the chair + man weighs = 70(9.81) ~ 700N





then each support will have a 350N force acting on it. Assuming the distance from one support to the centre of mass of one side is equal to the other.In case of office chair model,it controls our weight on it's two legs.what are the forces responsible there?
You could insert four small coasters (like on the legs of a stool) at four distant points on your S-shaped two-legged chair and it would have only four points of contact with the floor (like an ordinary chair). If you now sit on the chair in any manner that keeps the center of gravity of your body inside the area of the four coasters it will not tip over. The present legs of your chair merely distribute the weight over a larger contact area without changing the potential to tip over.