Recent content by italicus

@lukka98 Have a look at post #30, which refers to a diagram that I posted in another discussion , one year ago . Look at the diagram. Both OE and OT know that c is the same in all inertial reference frames; OT is reached by the light coming from B before than the light coming from A; (of course...

I don’t agree with you. I have cited Fabri as my reference author, you are free to think differently. Which literature, please? Make some example! It seems that I am fighting a battle against a lot of you, here , every moment… I have simply given an example to DA693, to make him understand . We...

Well, I consider my reference authors, among which there is professor Elio Fabri, previous teacher at the University of Pisa. Ever heard? Look for him on the web.

@DA693 Be careful. First of all, a “reference frame “ isn’t a system of coordinates; a rf is made of physical bodies to which you refer you state: for example, in your room a rf can be represented by floor and walls. Only after you can choose coordinates, f.e. the distances from the walls. Math...

Sorry but this is an idea of yours. Having well in mind that the real force is the centripetal one , consider that , more o less, we live in a rotating reference frame, the one of the Earth, and say that the acceleration of gravity , in this rotating frame to which we belong, is less at the...

The centripetal force is directed towards the axis of rotation.

Don’t worry, I am very careful. After having introduced the issue, I receive a lot of questions, to which I start answering with great patience and details, and it takes a lot to arrive at the right conclusion. I am accustomed to discussing with people.

AS you well know, non inertial forces are considered in non-inertial r.f. only .

Intuition must be put aside. But it isn’t mathematics only, it’s physics. An astronaut experiences greater blood pressure in his brain, he can loose senses. This is the way I teach the problem to students.

Optical illusion? During their training , astronauts are put into a centrifuge, and experiment accelerations many times greater than g . Centrifuges are used in chemical laboratories to separate heavier particles. Centrifuges are used in washing machines. The problem with inertial forces is...

It seems so simple to say , but we have to deeply thank Galileo, Newton and others. Let me make a short digression, forgive me. For almost two thousand years the scientific world was pervaded by the Aristotle ‘s physics, now we know it was wrong. He spoke of four elements, Earth water air and...

The main reason why F=ma and not m+a, further to dimensional nonsense, is that a material particle of mass m remains at rest wrt to your reference frame , supposed inertial, if it was initially at rest and no force F acts on it. But not only: because a = dv/dt is the derivative of velocity wrt...

Going back to the Einstein sentence. Consider the Earth, and its poles. It is possible to connect them by means of infinite meridians , not only one. Meridians are “ Straight lines “ for a bidimensional being living on the surface. But consider also two any points P and Q on the sphere. A...

When F=0, any mass, as big as you want, has zero acceleration , as stated by the first principle of dynamics, which exists indipendently by the second. Remember the story of the Newton’s “Principia mathematica “. Anyway, a = 0/0 has no mathematical or physical meaning. You lose not only...

Please justify your opinion by physical issues. Here we are speaking of what Physics says, not you or me.