What would happen if the gravity on Earth was suddenly turned off?
Our third grade class has been studying gravity and the motion of objects. We had a question: If the Earth no longer had gravity, would buildings and other structures attached to the Earth float away?
We would like to start our answer by saying that we're sure you realize that this could never happen. The Earth has mass, just like every other solid object does (including you). It is the Earth's mass that causes it to have gravity, and so in order to not have gravity the Earth would have to not have mass. But if the Earth didn't have mass, it wouldn't be there anymore!
Having said that, though, let's now imagine that we could magically turn off the gravity while leaving the Earth behind. What would happen to the things on Earth depends on how they are attached. As you know, the Earth is rotating at quite a speed (you're moving at over a thousand miles per hour at the equator due to the Earth's rotation alone). Now if you spin something around your head on a string, it goes around in a circle until you let go of the string. Then it flies off in a straight line. If the circle is very big, then at first the straight line is almost the same as the circle -- however, after a short amount of time, the two paths will be very different, since the circle bends around but the straight line does not.
"Switching off" gravity is analogous to letting go of the string. Things not attached to the Earth in any other way would fly off into space in a straight line that would take them away from the surface of the Earth. In buildings, people would start floating gently upwards until they bumped into the ceiling. Outdoors, however (or in buildings with GIANT ceilings), things would start floating away from the Earth gently but eventually go much faster, as their straight lines took them farther and farther away from the circular path that the spinning Earth takes. The Earth's atmosphere itself would also float off into space, for the same reason! Some things (like trees and most buildings) are rooted into the Earth. They would not fly off because they are being held down. In fact, the force you would need to hold on and keep yourself from flying away from the Earth is very weak, only about 0.3% as strong as the force of gravity (and even weaker away from the equator). However, things which are holding on to the Earth would eventually have problems too -- the Earth itself would most likely break apart into chunks and float off into space, since it is only held together by gravity also!
Anyway, we hope that you enjoyed the answer. Like we said to start with, though, you should remember that this could never happen!
Get More 'Curious?' with Our New PODCAST:
- Podcast? Subscribe? Tell me about the Ask an Astronomer Podcast
- Subscribe to our Podcast | Listen to our current Episode
- Cool! But I can't now. Send me a quick reminder now for later.
- Does your weight change between the poles and the equator?
- What would happen if an impact caused Earth to stop rotating?
- Does gravity vary across the surface of the Earth?
How to ask a question:
If you have a follow-up question concerning the above subject, submit it here. If you have a question about another area of astronomy, find the topic you're interested in from the archive on our site menu, or go here for help.Table 'curious.Referrers' doesn't existTable 'curious.Referrers' doesn't exist
This page has been accessed 103647 times since October 1, 2002.
Last modified: June 6, 2005 5:41:55 PM
Ask an Astronomer is hosted by the Astronomy Department at Cornell University and is produced with PHP and MySQL.
Warning: Your browser is misbehaving! This page might look ugly. (Details)