Re: Heliocentric Speed Change Problem
« Reply #20 on: January 04, 2019, 02:30:53 PM »
You opened this thread with a video link Tom so here's another one with a different view to you. 

There are subtle clues visible in the sky over the course of a year that show us that the Earth is moving through space at said speeds.  No equipment other than your own eyes needed to see them.
« Last Edit: January 04, 2019, 02:33:33 PM by shootingstar »

Re: Heliocentric Speed Change Problem
« Reply #21 on: May 03, 2019, 09:12:38 PM »
Years ago there was a student that came up with a intriguing question. He said: 

A car is running at 60km/h in a perfect straight concrete road, all four tires are touching the ground.
The bottom of the tires that touches the ground are unquestionable stopped in reference to the ground.
The upper part of the tires are speeding at twice the speed of the car.
The front of each tire, speeds as the car, but reducing speed, they need to stop when touching the ground.
The back of each tire, speeds as the car, but increasing speed, they need to be double speed on top.
The question was:  how the tire stands this constant acceleration and breaking once per revolution, without damaging? and why we don't feel such "bumping" speed change in the tires?

It took a while to make the students to "see the magic". 
Our brain is unable to by itself catch the idea of certain physical forms or movements.
The only way to start to grasp such light, is thinking; after the car/airplace accelerated and reach some steady speed, it flew few inches in the air.
During this minute, even that the tires are continuing rotating and "almost touching" the ground, and coincidentally they seems to be touching the ground and stopped while doing that, they are not.
In reference to the car and shaft, the tires are in a perfect circular motion, no breaking, no accelerating whatsoever. The centrifugal force on the rubber is perfectly balanced.  What is breaking is the reference to the ground, and as a reference it does not, and can not change anything in the rubber movement.  The surface and angular speed of any part of the tire rubber is exactly the same in reference to the shaft and car.

The same, the illusion of Earth's different speed on the illusion of forward and backward motion due its spinning.  You can find a ton of formulas and calculate several variables and came up to nice conclusions, but in real, it doesn't happen, you can't even measure it, because it doesn't exist.  It doesn't change a bit if the Earths is moving forward or backward in its path around the Sun, the spinning around its own axis cancels any angular vector.  The centrifugal force is equal based on the frame of reference, and doesn't change if you have the pivoting point moving in a constant speed.  What you have is a constant centrifugal force, that in case of Earth's is minuscule compared to the space deformation sliding vector.  Of course, you can have differences IF the pivoting point speed changes, that is not the case of Earth.

You can make a nice and easy experiment.  Remote the front bicycle wheel from the bicycle, cut 20 pieces of a light string 50 cm each, find 20 objects like large metallic nuts or solid 50+g objects (same size rocks or even little bags of sand), tie the objects to the end of the strings, and tie the other side of each string to the bicycle wheel equally spaced by 18 degrees.   Now, hold the wheel horizontally and rotate it until all the strings and objects spread aside in an angle around 45° by the centrifugal force, so you will be able to see any difference of speed, if they speed up the string will climb to a higher angle, if they slow down, the string and the object will go down.  Now, while it rotates happily, and holding the wheel in a way you could walk, start to walk forward holding the rotating wheel, keep an eye on the angle of each string.  Adjust your walking speed in order for the "backward motion" coincide with the ground, so they appear as stopped, and tell me if any string performing the "backward" movement goes down due low speeding or the forward movement would climb in angle for having a greater speed.  They would not.  If you run much fast, or attach the wheel to the hood of your car and run, the air movement will interfere with the results. 


Offline QED

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Re: Heliocentric Speed Change Problem
« Reply #22 on: May 04, 2019, 03:01:19 PM »
This is by a wide margin the most accurate and complete explanation for relative motion I have read on this forum.

You certainly must have taught physics or have equivalent training. This makes it even more strange to me your prior diatribe regarding gravitation. It was filled with imprecise language, poorly constructed arguments, and an apparent ignorance of the normal force - which one learns in physics I.

Can you help reconcile for me this difference? Are there two of you?

In any event, I redact my stipulation to leave the physics to me. You clearly have valuable (albeit inconsistent) input.
The fact.that it's an old equation without good.demonstration of the underlying mechamism behind it more invalid, not more valid!

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Re: Heliocentric Speed Change Problem
« Reply #23 on: May 04, 2019, 04:34:41 PM »
Thank you, QED.   I wish we could have only good days in life.