About falling bodies **Galileo***, years ago, tells how two mobiles with different *“weight”* but equal density move with equal speed, trying in this way to disprove an Aristotle’s statement…

*“mobiles of the same material and different weight, when moved through the same medium, receive velocities proportional to their weights“*

Galileo’s **disproof** is based on a very simple reasoning… not very appropriate to discredit Aristotle, father of the Logic… and on the ambiguity of the term “weight”… indeed this disproof comes from a radical change of scenario, since Galileo takes approximately the example of apples, now smaller now bigger, falling vertically in his garden…

Aristotle’s **mobile** is instead a celestial body moved by his Prime Mover, moving in his Universe of concentric Spheres and describing a Perfect Motion… what’s more, for Aristotle cause of the movement is always a force…

So, for celestial bodies, ** “weights”** are the

**forces**acting on them, originated by a Prime Mover and directed towards Eutòpia*,

**are the ones received by the rotation of the**

*“velocities”***concentric Spheres**, causes of the movement.

**Observation and Logic** lead Aristotle to say that, for mobiles in circular motion, the rotational speeds of their concentric Spheres are proportional to the forces pushing them towards Eutòpia, in such a way that the mobiles are always in a condition of equilibrium… rotations constantly preventing the mobiles to fall on Eutòpia.

Let’s consider a **Satellite** revolving around a **Planet**…

- its momentum depends on its matter
- the gravitational force acting on it depends on the power of its Center of force

Let’s suppose, now, to have, on the same orbit (at the same speed), a Satellite with double amount of matter and double volume, considering that, for a sphere, doubling the radius is more than doubling the surface, which is more than doubling the volume…

- its momentum would be double
- the power of its Center of force would be most likely less than double

consequently the gravitational force wouldn’t be able to bend adequately the trajectory of the *“double Satellite”*… i.e. the old orbit would be no longer appropriate to the new Inertia of the Satellite… then, necessarily, the *“double Satellite”* will go to occupy a more external orbit, on which it will find again an **equilibrium ratio** between ** “velocity”** and

**.**

*“weight”*So **bigger Moons**, with equal density, occupy **slower orbits** on which they are ** “lighter”**.

*******

**Eutòpia** ⇒ Planet Earth and Aristotle’s Center of the Universe
**Galileo** ⇒ Galileo Galilei

Different Weights

May 22, 2021