Jan Peter Apel

Mystery Acceleration

Accelerations are vectors, ie they consist of one value and one direction. The directions are generally ignored. Why? Answer: "One know that, one do not need to measure that extra!" For real?

1) Straight Acceleration

The video shows the accelerations when starting and then braking a car. The digital display inside the steering wheel and outwards the trees / bushes at the roadside indicate the speeds. Within the accelerometer can be seen how the sensor mass must be accelerated by the measuring spring.
If the sensor mass moes backwards, the acceleration of the car and the 
accelerometer is forward.
Movement of sensor mass forward indicates a brake deceleration (negative acceleration).

The rule for reading this open accelerometer is:

The sensor mass, accelerated by the measuring spring, always goes in that direction
from which the external acceleration force for acceleration acts.

2) Circular Acceleration

The video shows the accelerations in curves.

As you can see, the sensor mass moves outwards. So an acceleration force acts from the outside inwards to the center of the curve. That's a surprise, as we believe that a force works from the inside out. And we even gave this force a name: centrifugal force.
Wrong! There is no centrifugal force!

Although this is known in higher education, bt it has not yet penetrated to primary schools and their textbook wriders.

For a car to be able to make a turn, a force is needed that pushes it steadily from the outside inwards to the center of the curve. This force is the centripetal force and arises as friction between the tire and the road. In the case of black ice, it is almost zero and the car can not turn.
This centripetal force is the action force, that makes cornering possible.
The centrifugal force is only the reaction force, which one should not have given any name

3) Vertical Acceleration

Now it is even more surprising. The accelerometer is aligned vertically
What does it indicate? That gravity moves the sensor mass down. That's what everybody says, but: Wrong!

The accelerometer is a measuring device. That has no idea in which direction it measures. It measures accelerations, it can not and may not do more than that and it does not.
Measuring instruments never lie! If they could, they would no longer be usable and the entire physics would be on false feet.
What did Einstein say?
He said, that our weight is also arise out of an acceleration. Namely a Newtonian acceleration, so by an external force to us.
He explained it with a person in an elevator cabin, which is accelerated upwards in the open space from the elevator floor. The human being feels the same "heaviness" as here on earth. And he added explicitly that there is no severity wight besides the.acceleration force, which we only feel as a "gravity heaviness"

Exactly this acceleration from bottom to top measures our and all other accelerometers. But nobody wants to believe it.
But who do not believe measuring instruments should not believe anything at all, because measured values are the foundation of all physics.

DThat an acceleration acts to us from bottom to top is a fact. To get a bit closer to this mystery, the following last experiment. We measure the acceleration in free fall.

4) Gravitational Acceleration

As you can see, the accelerometer schows a zero acceleration. The falling body is not accelerated at all.
It also does not act a Newtonian power to the boy. "A falling bodie is forces-free, so free of acceleration" was Einstein's great insight on which he built the general theory of relativity. Accelerometers with the measuring principle by a sensor mass can therefore not measure gravitational accelerations, only Newtonian's, caused by Newtonian forces.

The measurement results:

A Newtonian acceleration force acts on us from bottom to top
But gravitational accelerations are free of forces, so there is no attraction at all, at least not as Newtonian force.
Asserting the force of attraction as a "non-Newtonian" force is an invention, so as not to have to admit that one does not know why a body accelerates in free fall.
All this only clears up when the mystery of gravity is deciphered.

The Newtonian acceleration from bottom to top is necessary
so that we are not fall with the mystery of gravity.

Te cause of gravitation is by no means an attraction force.

The Newtonian acceleration upwards is also possible above the ground due to the recoil force from backpack nozzles or by air masses pushed downwards by wings.

Einstein is right that bodies on celestial bodies are accelerated from bottom to top, what they perceive as weight.
But he is wrong with his theorie of relativity, because he regarded as a basis only a force-free body, but not an also movement-free body.