Why is escape velocity affected by Earth's rotation velocity but not Earth's orbit velocity ?

Question

It is said Earth's rotation velocity affects rockets escape velocity. Then should Earth's other motions like our solar orbit motion also affect escape velocity ?

Answer 1

Because the earth is in freefall around the sun, the centrifugal force (from orbit) and gravity (from sun) pretty much cancel out to first order in calculations where the earth is your frame of reference, so you can ignore them both except for extremely precise calculations.

Answer 2

And who said the orbit's velocity does not affect rocket velocity? It does, just like the rotation velocity. Velocity is velocity, they are vectors and they add/subtract no matter what the origin of the velocity might be.

But, see, the deal is this. When we talk about rocket velocity (e.g., escape or orbital), we typically do so relative to the Earth's center. So Earth center is the basis for all changes in distance over time (velocity). Earth's center is set to zero distance and velocity; it becomes something like the zero point on an X-Y graph.

Velocity has to be measured relative to something. It's something like measuring how fast we can jump in an elevator. We don't add in the rotation of the Earth to that velocity because we are really interested in the velocity relative to the floor of the elevator. So the floor becomes the zero point.

On the other hand, if we were to calculate rocket velocity relative to the Sun's center, we'd certainly need to fold in Earth's orbital velocity as well as its rotational. And, to carry this even further, if we want to know how fast that rocket is going relative to the center of the Milky Way Galaxy, we'd need to fold in the Sun's velocity as well.

As Einstein once said "It's all relative."

Answer 3

Becuse of relativity principle.
I do not mean special relativity, I mean good old
Galilean relativity (if you ride in a car, windows closed...)

When we speak of escape from Earth gravity,
relative speed of Earth does not matter.
In every inertial frame of reference escape velocity
(defined as relative velocity of satellite to Earth)
must be the same.

Rotation of Earth on the other hand is absolute,
and can (and does) alter escape velocity.

For this very reason if we want the satellite to
escape from solar system, then orbital speed
of Earth is of great importance, while the speed
of the Sun itself with respect to the Galaxy does
not matter.

Answer 4

it would want to take an merchandise the dimensions of mars that could collide with the earth to do any form of alteration to the earth's rotation because no longer even each of the nukes that humanity has can do some thing that could substitute the earth's rotation. in spite of each thing, the earth did flow by tens of millions of years of asteroid bombardment and did not get any form of rotational transformations until eventually a huge merchandise the dimensions of mars hit it that made the earth spin and sweetness the moon besides. no matter if i'd be incorrect considering that that's only a concept by technique of scientists that I study and watched on nationwide Geographic.

Answer 5

"Escape" is relative to the surface of the earth, so only momentum derived from surface rotation (relative to escape from the earth's gravity) is applicable.

If you were to speak of 'escape' from the solar system, then the momentum of the earth around the sun plays a small part in that velocity (an extremely small part, though).

.

Answer 6

Because there are many fact that conclucrate to this:

1) the gravitational force to the sun is _not_ cancelled by the centrifugal force (the second one is irreal) so one of the answers is bad

2)one of the causes is that the distance Sun-Earth is so high that the gravitational force Sun-Earth is cancelled (in the first approximations, hint:Taylor series) by the gravitational forces Earth-other planets

3)the solar orbit speed is to low to be counted for in the first approximation (Taylor series)