## THE PHYSICS OF ARTIFICIAL GRAVITY

The earth’s gravity constantly pulls us (and everything else that stands on its surface) towards its center : that’s why there’s an " up " and a " down ", and why we can walk on the street and get back to the ground when we jump... This pull has a numerical value of 9,82 meters per square second, and is commonly referred to as being 1 " G ".

The goal of artificial gravity is to reproduce the effects of this pulling strength in environments where gravity is otherwise non-existent, such as in earth orbit. There are two ways of generating artificial gravity fields : one is to call Scottie in engineering, and the other is to get our environment to turn around some central point. We will focus on this second method... !

Those who haven’t forgotten their high-school physics remember that the centrifugal acceleration in a rotating circular structure is given by :

(1)that is : the square of the speed (v) divided by the radius (r). The speed is really the distance (d) divided by the time (t), so let’s replace the above " v " by that :

(2)In the case of a circular trajectory, the distance (d) is the famous :

(3)If we insert formula (3) into (2) we get :

(4)If we measure the radius " r " in meters and the rotational speed " t " in seconds, the artificial gravity generated, in units of " G " is given by the following equation :

Or in a simplified approximation :

This means that the pulling strength (or centrifugal force) generated within a rotating structure, is proportional to the radius of the structure : the longer the radius, the stronger the force. It is also proportional to the square of the rotational speed : the faster the rotation, the greater and greater the force !