| If the rest of the universe had earth's gravity,
would we be floating? And if so, how high would we
Well, what do you mean by the rest of the
universe having the Earth's gravity? Gravity is a
force between two massive objects - Earth's
gravity is the force that attracts us (and
everything else) to the center of the Earth, but
what would the universe's gravity be? In which
direction would it pull us?
More importantly, if something in the universe
were attracting us towards it, it would also
attract the Earth as well. So both we and the
Earth would be pulled towards this massive object,
but in the meantime, we would continue to be
pulled towards the center of the Earth as well,
and stay planted on the surface of the Earth.
Even if the rest of the universe had earth's
gravity, we would probably not float, since the
earth has a strong enough gravitational pull to
keep humans and other objects that are much less
massive than the earth, from floating away.
The strength of gravity depends on the mass of
the object divided by the square of the distance
from that object's center. On the surface of the
Earth, this is approximately ten meters per second
per second (actually slightly less, but a first
approximation). An Earth-sized planet elsewhere in
the universe with the same mass of the Earth would
have the same gravity.
It doesn't matter how much mass other things in
the universe are when we're on the Earth because
everything around us, including the Earth itself,
is just as subject to their gravity as you are.
You don't feel the gravity of the sun, for
example, because the Earth is experiencing the
same pull from the sun, and, as a result, is
orbiting the sun just as you are. You notice the
Earth's gravity only because you are standing on
it and the surface of the Earth prevents you from
falling deeper towards the center. An astronaut on
the space station experiences over 90% of the
gravity you experience on the Earth's surface, but
doesn't feel it because the space station and
everything on it are "falling" at the same rate -
it is their horizontal velocity that keeps them in
orbit instead of falling to the surface.
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