# Tagged Questions

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### Can gravity be reversed?

I'm wondering if any set of hypothetical conditions could result in us gravitating in a different direction. Specifically a reversal of gravity on the surface of Earth (or at least part of it), so ...
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### How do I explain to a 6 year old why people on the other side of the Earth don't fall off? [closed]

Today a friend's 6 year old sister asked me the question "why don't people on the other side of the earth fall off?". I tried to explain that the Earth is a huge sphere and there's a special force ...
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### how apparent weight varies due to the rotational motion of earth

I learned that as the earth rotates about its axis, the bodies on the earth also follow a circular path. In most books I read, they give the example of a person standing on a weight balance at the ...
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### Gravity change as a function of time only

Is it possible to find how gravity changes with time? That is, height is not part of the equation. For example, $g$ can be expressed as a function of height that does not involve time with this ...
1k views

### No uncertainty for standard gravitational acceleration?

The other day I asked about the uncertainty of light, and this issue triggered me to start looking into other physical constants and try to understand why other constants have no uncertainty. One of ...
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### How faster is the effect of force exerted by gravity? [duplicate]

We all know that Earth revolves around the Sun due to Gravitational force of the Sun. Also we know that it takes just over 8 minutes for the Sun's light to reach Earth. Now let us say, hypothetically ...
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### Why does earth spins? [duplicate]

I understand the governing force causing the earth's cycle around the sun is gravity. It can be described by Keplar's law. But what causes the earth's spin? what is its governing law?
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### How do “gravity hills” work?

There are many "gravity hills" throughout the world http://en.wikipedia.org/wiki/Gravity_hill I just visited one here yesterday in Burkittsville, Maryland: http://www.roadsideamerica.com/tip/600 ...
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### Does gravity change the closer you are to the Earth's core? [duplicate]

Very simple question that has bugged me for some time, does the acceleration produced by gravitation (e.g. $9.8\: \mathrm{m/s^2}$) would change if we placed an observer closer to the planet's core? I ...
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### Could we use the coriolis effect to travel

Given a platform that is floating independent of Earth's gravity, would it be possible to put a platform over the equator and over the day, would the Earth rotate from under it allowing you to travel ...
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### How would gravity change on a planet rotating around itself very fast?

Let's take a planet identical to Earth, but with rotation speed multiplied by ten thousand. What would happen with the gravity if it was spinning madly around itself? Would the centrifugal force make ...
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### Speed of the Moon

Why the motion of the Moon looks very slow in the sky? Doesn't it need the high speed in order to escape the earth's gravity?
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### How does earth carry moon with it, if it can not force moon to touch it by gravitational force?

earth's gravitational force is acting on its moon in such a way that it forces moon to rotate round its orbit by centripetal force and carries it while rotating round the sun by gravitational force. I ...
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### Does the Earth have a semi-solid body at its core because of lower pressure at the center of the Earth?

I have read that the Earth has a semi-solid iron body at its core, even though that object is surrounded by liquid magma.... I'm wondering if this is because of a pressure (and resulting temperature) ...
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### If the Moon had gravity as good as the Earth and a magnetic field could it have supported life?

If the Moon had gravity as good as Earth and a magnetic field could it have supported life? Because if the Moon had gravity, it could have retained water more than is present today on the surface. ...
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### Deviation from Earth's orbit

How much orbital deviation is required for the Earth to get knocked out from current orbit so it either moves away from Sun or towards the Sun?
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### What is the gravity at the center of the Earth? [duplicate]

Possible Duplicate: Would you be weightless at the center of the Earth? Supposing there is a cavity at the center of the Earth, what is the gravity there? What will be its direction and ...
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### If the earth would stop spinning, what would happen?

What would happen if the earth would stop spinning? How much heavier would we be? I mean absolutely stop spinning. How much does the centrifugal force affect us? If you give technical answers (please ...
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### Could we make a trebuchet that could launch objects to a stable orbit?

Inspired by this xkcd, which calculated the energy requirements for accelerating individual humans to escape velocity (regardless of consideration for what that would do to your organs), I am ...