How does gravity work? What makes things fall to the
ground on earth, whilst things float in space and on the moon?
Could you please explain this in simple terms please?
Well, we really don't know how gravity works, but we definitely know its
effects. Gravity is the attraction to bodies of mass have on one another.
Mass is a measure of how much stuff something contains. Depending on how
big the two masses are, and depending on how far away they are from one
another's center determines the strength of the gravity force. Because you
are on planet earth (a very large mass) and very close to its center, you
are very attracted to its gravity pull although you may have a small mass.
Now, the farther away you get from the center of the earth, the less the
pull of gravity affects you. In space, you and your space ship are not
being pulled very much by earth's gravity because you are far away from its
center. However, you both are still being pulled back to earth because
gravity is still working on you. You and your ship just happen to be
falling back to earth at the same rate, so it just seems like you are
weightless and things are floating in space. On the moon, the gravity pull
is less than that of earth's (because it is a smaller mass). Therefore,
things fall at a slower rate on the moon than they do on earth, so it seems
that things "float" on the moon. No mater where you are in the universe,
gravity is pulling on you from somewhere because there are all of these
bodies out in space that have mass.
I suggest you go to your local library to look a little more into the
affects of gravity. Look for a book on Sir Isaac Newton. He is one of the
first scientist to really study gravity and its affects on the universe.
Also, you might want to look into some books that talk about "The Vomit
Comet". "The Vomit Comet" is a plane that NASA uses to simulate
weightlessness for astronauts who are about to go into space, but need to
practice how to handle weightlessness while still on earth. Good luck.
Click here to return to the Physics Archives
Update: June 2012