Release speed

General scientific debates. Presentations of new technologies (not directly related to renewable energies or biofuels or other themes developed in other sub-sectors) forums).
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Exnihiloest
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Re: Release speed




by Exnihiloest » 18/05/21, 19:39

Obamot wrote:...
You just edited since then and put “moderate” in parenthesis. To avoid any new misunderstanding, we need local behavior: so let's set an ethical and proportionate basis for reflection if you will?

If you want me to tell a shrink about it. I am absolutely not opposed to it. So you'll have to show you specific and put a link to the offending post that would trigger all this (I'm not asking you for a tedious search, only one is enough, and not 3 weeks back, eh ...).
...

There I will not prove you wrong. The offending remarks must be clearly shown, and why. And if it is a moderation worthy of the name, the moderation is done on the form (elimination of insults, slander, flooding, calls to hatred ...), not on the substance.
As far as I'm concerned, that was the case except once, when I had a warning for all of my work. : Lol: , without any targeted link.
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Re: Release speed




by Obamot » 18/05/21, 19:43

Exnihiloest wrote:without any targeted link.
Pan on target.
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dede2002
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Re: Release speed




by dede2002 » 19/05/21, 18:39

ABC2019 wrote:
Gildas wrote:
ABC2019 wrote:when he ran out of fuel :).
)

If the plane quoted by Guy le x15 takes off to immediately reach an altitude of 100 km and wants to go to space, it will not run out of fuel! Even if the plane has no lift and goes vertically with the engine at full power, it will not move forward! Why ???

why are you saying he won't move on? if there is a push, it will move forward. The problem is that the rear-wheel drive is very unstable and with no lift from the atmosphere it might fly anyhow, rockets have sophisticated stabilization mechanisms to prevent that. On the other hand the mig do not carry oxidizer to my knowledge.


How could there be a push out of the atmosphere, an airless reactor is like a boat propeller without water!
He would have to eject his own weight constantly to have a push of 1g ...
The speed quoted is a circumferential speed, so that the centrifugal force exceeds the force of attraction, not a perpendicular speed.
Speed ​​compared to what? We start near the equator to gain momentum, so it's not the speed over the earth that counts ...?
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Re: Release speed




by GuyGadeboisTheBack » 19/05/21, 18:43

So, does he take off or not the plane which is not moving? : Mrgreen:
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Re: Release speed




by Obamot » 19/05/21, 19:52

I have the impression that the Eclectron-Evaluation-Gildas platform has taken water and the zinc from the magnetic motors no longer comes off the holder.crayonplane, it's very bad for Karma and its biodegradable metal-free batteries will melt like snow in the Sun : Cheesy:
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Re: Release speed




by ABC2019 » 20/05/21, 00:09

dede2002 wrote:How could there be a push out of the atmosphere, an airless reactor is like a boat propeller without water!

Oh yeah ?

well will have to explain to me how the LEM took off from the Moon then ....
He would have to eject his own weight constantly to have a push of 1g ...


absolutely not. A rifle that fires a bullet has a recoil acceleration much greater than 1g, while the bullet is much lighter than a rifle. Think again.

The speed quoted is a circumferential speed, so that the centrifugal force exceeds the force of attraction, not a perpendicular speed.
Speed ​​compared to what? We start near the equator to gain momentum, so it's not the speed over the earth that counts ...?

the direction of the speed does not matter (good on condition of not going to crash on the ground anyway).

I made the calculation of the mechanical energy, the direction of the speed does not intervene in it.
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Re: Release speed




by Exnihiloest » 20/05/21, 18:52

dede2002 wrote:...
How could there be a push out of the atmosphere, an airless reactor is like a boat propeller without water!

Because a rocket takes away its oxidizer in addition to its fuel, and both are ejected.

...
The speed quoted is a circumferential speed, so that the centrifugal force exceeds the force of attraction, not a perpendicular speed.
Speed ​​compared to what? We start near the equator to gain momentum, so it's not the speed over the earth that counts ...?

Yes.
It surprises a lot of people. At the altitude of the ISS, gravity is not much different from what it is on the surface of the earth. But the centrifugal acceleration linked to the rotation of the ISS around the earth exactly compensates for the terrestrial gravity, hence the local state of weightlessness (consequence of Einstein's equivalence principle: the acceleration of gravity is indistinguishable from a "mechanical" acceleration, ie by speed change. The two are composed as if they were of the same nature, even causing the same relativistic effects, such as time dilation).
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ABC2019
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Re: Release speed




by ABC2019 » 20/05/21, 20:05

Exnihiloest wrote:It surprises a lot of people. At the altitude of the ISS, gravity is not much different from what it is on the surface of the earth. But the centrifugal acceleration linked to the rotation of the ISS around the earth exactly compensates for the terrestrial gravity, hence the local state of weightlessness (consequence of Einstein's equivalence principle: the acceleration of gravity is indistinguishable from a "mechanical" acceleration, ie by speed change. The two are composed as if they were of the same nature, even causing the same relativistic effects, such as time dilation).

in fact this is the case in all movements in free fall, where only gravity acts: it also works in an elevator whose cable has been cut .. but it lasts less long : Mrgreen:
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Re: Release speed




by dede2002 » 21/05/21, 06:01

Thank you I got it, or almost ... :)

The direction of the speed may not matter. but it is easier to reach a horizontal speed than uphill.
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Re: Release speed




by ABC2019 » 21/05/21, 06:21

dede2002 wrote:Thank you I got it, or almost ... :)

The direction of the speed may not matter. but it is easier to reach a horizontal speed than uphill.

with a very short pulse time, no, it's the same. A rifle bullet comes out at the same speed no matter which direction you shoot. You have in the head the speed of a car, but precisely we are in the case of a gradual push, and the difference comes from the fact that you have to overcome the potential energy during the acceleration time when you go up, while you don't have to do it horizontally. with the same power expended at the start, the speed achieved includes the fact that you expended part of the energy to go up in one case, and not in the other.

But without friction, for example on the Moon, a bullet which would reach the speed of release will escape the attraction of the Moon whether it is fired vertically or horizontally ...
.
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