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### Release speed

published: 10/05/21, 12:20
Hello,

If someone will explain to me "the speed of liberation" to escape a star ... For the Earth it is 11,2 km / s (or 40 km / h).
Why an airplane (while heading immediately vertically) cannot escape if it only goes to mach 1 if it takes its oxidizer / fuel on board! He won't stop if he goes to mach1 ??
The speed of release, or speed of escape or escape is, in physics, the minimum speed that a projectile must reach to definitively escape the gravitational attraction of a star (planet, star, etc.) devoid of atmosphere and move away from it indefinitely. This speed is all the more important as the mass of the star is important and the object is close to its center. Relative to the star, it is a scalar value (its direction plays no role). This speed is greater than the minimum orbiting speed necessary for the object to be able to place itself in orbit around the star.

https://fr.wikipedia.org/wiki/Vitesse_d ... 3%A9ration

### Re: Release speed

published: 10/05/21, 12:31
Gildas wrote:Hello,

If someone will explain to me "the speed of liberation" to escape a star ... For the Earth it is 11,2 km / s (or 40 km / h).
Why an airplane (while heading immediately vertically) cannot escape if it only goes to mach 1 if it takes its oxidizer / fuel on board! He won't stop if he goes to mach1 ??
The speed of release, or speed of escape or escape is, in physics, the minimum speed that a projectile must reach to definitively escape the gravitational attraction of a star (planet, star, etc.) devoid of atmosphere and move away from it indefinitely. This speed is all the more important as the mass of the star is important and the object is close to its center. Relative to the star, it is a scalar value (its direction plays no role). This speed is greater than the minimum orbiting speed necessary for the object to be able to place itself in orbit around the star.

https://fr.wikipedia.org/wiki/Vitesse_d ... 3%A9ration

the speed of release is that which is necessary to escape the attraction of a star without being pushed , therefore a ballistic movement "all engines off". It works for a cannonball for example (cf. From Earth to the Moon by Jules Verne), but not for a plane or a rocket that has a burning reactor. with a continuous thrust one can very well escape an attraction with a speed of 1 m / s ...

### Re: Release speed

published: 10/05/21, 14:43
Thank you for answering. But maybe I misspoke .... Why does it take 40000 km / hour to escape the pull of the earth? If an airplane takes off vertically and only reaches Mach 1 speed (while carrying its oxidizer / fuel), why will it stop? If he even succeeds in going to mach 10 why will he stop too?

### Re: Release speed

published: 10/05/21, 15:22
Gildas wrote:Thank you for answering. But maybe I misspoke .... Why does it take 40000 km / hour to escape the pull of the earth? If an airplane takes off vertically and only reaches Mach 1 speed (while carrying its oxidizer / fuel), why will it stop? If he even succeeds in going to mach 10 why will he stop too?

I too may have expressed myself badly ... if you have an engine, it is not necessary to reach 40000 km per hour to escape the attraction of the earth. This is only necessary for an object which does not have its own means of propulsion, and which is launched near the surface of the Earth.

### Re: Release speed

published: 10/05/21, 15:29
Indeed it is valid for a meteorite, but we are on the surface of the earth and the planes too

### Re: Release speed

published: 10/05/21, 15:47
Gildas wrote:Indeed it is valid for a meteorite, but we are on the surface of the earth and the planes too

but planes have an engine so do not have to reach this speed

### Re: Release speed

published: 10/05/21, 16:40
No one else to answer?

### Re: Release speed

published: 10/05/21, 17:29
Gildas wrote:No one else to answer?

pff don't you trust? do you want the mathematical demonstration?

### Re: Release speed

published: 10/05/21, 17:43
Gildas wrote:No one else to answer?
Same answer as before.

https://fr.wikipedia.org/wiki/Vitesse_d ... 3%A9ration

Basically, during the Apollo 13 Mission tragedy, when the capsule broke down, the astronauts used the impulse they had during the orbit to circle the moon and be able to come back to Earth. , but if they hadn't been able to ignite the engine of the LEM that flicked to escape the lunar pull, they would have died in orbit around the moon.
https://www.cieletespace.fr/actualites/ ... -en-succes

### Re: Release speed

published: 10/05/21, 18:10
We gravitate around the problem

(2nd edition)

If a Mig takes off with oxidizer and fuel in order to leave Earth to go into space at an altitude of 1000km, why should it exceed the release (or orbit) speed ??

If he's at Mach1 or Mach 2 or 3, why won't he leave Earth ???
Will it advance more at 40m altitude?