Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top
  1. Where the gravitational pull of Earth exist up to?

  2. What distance from Earth it will be zero?

  3. How do the skydivers fly at a same altitude?

  4. Won't they feel gravitational pull?

  5. What is the Earth's gravitational pull?

share|cite|improve this question

closed as off-topic by Brandon Enright, centralcharge, jinawee, Kyle Kanos, tpg2114 Jan 3 '14 at 15:30

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – Brandon Enright, Kyle Kanos, tpg2114
If this question can be reworded to fit the rules in the help center, please edit the question.

By changing their shape, skydivers can alter individual air resistance and velocity, and so can join up – Henry May 13 '11 at 7:37

The gravitational pull of the Earth is never zero; the force (and therefore the acceleration) decreases as you go further from the Earth like $1/r^2$ where $r$ is the distance from the center of the Earth. At altitudes equal to the radius of the Earth, $6378$ kilometers or so, the force drops to $1/4$ to what it is on the surface but it is not zero. It is not zero even at 400,000 kilometers from the Earth - which is why the Moon is orbiting the Earth.

You don't feel any Earth's gravitational pull on the International Space Station or on the Moon or on any orbit because the attractive gravitational acceleration is exactly compensated by the fictitious centrifugal force.

Skydivers may fly at the same altitude as other skydivers but all of them are attracted by the Earth and all of them fall down. Because of the air resistance, the skydivers velocity doesn't increase arbitrarily high. Instead, it ultimately converges to 200 km/h or so which is approximately 55 m/s. (Of course, it's the speed before they open the parachutes - if this were the speed after they open it, that would be pretty dangerous.) In the vacuum, you would reach this speed in 5.5 seconds.

So approximately after 6 seconds, the skydivers no longer accelerate. All of them are falling at the same speed. By changing the shape of your body, you may influence the air resistance which modifies your velocity - both speed and the direction. I've tried it, too. It's quite a wind over there.

share|cite|improve this answer
So I'm told, gravity propagates at the speed of light; There are parts of the universe unaffected by the Earth's gravity. – zwerdlds Apr 5 '13 at 18:31

protected by Qmechanic Feb 20 '13 at 21:49

Thank you for your interest in this question. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).

Would you like to answer one of these unanswered questions instead?

Not the answer you're looking for? Browse other questions tagged or ask your own question.