In sci.physics.relativity, Sanny

wrote
on Sun, 27 Apr 2008 00:53:37 -0700 (PDT)
:
When Sun and Earth are attracting each other why do Earth not fall on
Sun.


When we throw a big Stone in air It will Fall Back on Earth.
Simmilarly For Sun Earth is just a piece of Rock? Who do this big rock
Earth Fall onto the Sun Just like the Stones which we throw in air
just come back and hit the Earth?

Simmilarly why not the Moon fall on Earth by the Gravity attration?

Why are the planets revolving round the sun for so many years instead
of just falling onto the Sun?

When we visit Moon on a Rocket Our Rocket Just Falls on Surface of
moon So why these heavenly bodies not falling on Bigger one?

Bye
Sanny

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Best I can do here is an analogy; take a funnel and a
ball bearing. Drop the ball bearing in the center of the
funnel, and of course the ball bearing falls through the
neck of the funnel.

Drop the ball bearing at an offset, and various interesting
things happen, mostly because the bearing may bounce.
It does not immediately fall through the neck though it
depends on precisely how one drops the bearing.

*Roll* the ball bearing around the funnel, and watch it
roll around the funnel; because the funnel has friction
it will eventually drop through the neck but it'll take
a lot longer.

At least one book I've read suggests that a satellite
"falls around the Earth", which is also pretty close.

--
#191,
Q: "Why is my computer doing that?"
A: "Don't do that and you'll be fine."
** Posted from http://www.teranews.com **

The Ghost In The Machine wrote:
In sci.physics.relativity, Sanny

wrote
on Sun, 27 Apr 2008 00:53:37 -0700 (PDT)
:

When Sun and Earth are attracting each other why do Earth not fall on Sun.

When we throw a big Stone in air It will Fall Back on Earth. Simmilarly For Sun Earth is just a piece of Rock? Who do this big rock Earth Fall onto the Sun Just like the Stones which we throw in air just come back and hit the Earth?

Simmilarly why not the Moon fall on Earth by the Gravity attration?

Why are the planets revolving round the sun for so many years instead of just falling onto the Sun?

When we visit Moon on a Rocket Our Rocket Just Falls on Surface of moon So why these heavenly bodies not falling on Bigger one?

Bye,

Sanny

Best I can do here is an analogy; take a funnel and a ball bearing. Drop the ball bearing in the center of the funnel, and of course the ball bearing falls through the neck of the funnel.

Drop the ball bearing at an offset, and various interesting things happen, mostly because the bearing may bounce. It does not immediately fall through the neck though it depends on precisely how one drops the bearing.

*Roll* the ball bearing around the funnel, and watch it roll around the funnel; because the funnel has friction it will eventually drop through the neck but it'll take a lot longer.

At least one book I've read suggests that a satellite "falls around the Earth", which is also pretty close.


Sorry... I'll try once more.

Isaac Newton came up with the concept called "Newton's Cannon" to
explain the force of Gravity in orbital mechanics in a simple manner
(let's forget about atmospheric drag for now).

If you fire a cannon from a mountain top, the shot will eventually hit
the Earth if the initial energy (momentum) is low. It wants to follow a
straight line, but is being accelerated toward the ground, which will
eventually overcome the shot's momentum.

However, if I use more powder, the shot will never hit the ground.
Because of higher momentum, it's new trajectory has the same curvature
as the Earth's surface. It will go into permanent orbit and fall around
the Earth forever. (The equation for the initial Velocity is V =
SQRT(GM/r). Notice that there's only _one_ acceleration term - Gravity.)

Now... The Moon is falling around the earth in the same manner, but
it's momentum (its Centrifugal Force) is exactly balanced by the
acceleration of Gravity (its Centripetal Force) and it will orbit the
earth for a very long time.

However........ Because of the effect of the moon's gravitation on the
Earth's tides, the system is losing energy and the Moon is moving away
from the Earth at about 1.5 in/year. The Earth will eventually lose the
moon.

KL

In sci.physics.relativity, Keith L

wrote
on Thu, 08 May 2008 01:02:19 -0500
:
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The Ghost In The Machine wrote:

[snip for brevity]

At least one book I've read suggests that a satellite "falls
around the Earth", which is also pretty close.


Sorry... I'll try once more.

Isaac Newton came up with the concept called "Newton's Cannon" to
explain the force of Gravity in orbital mechanics in a simple manner
(let's forget about atmospheric drag for now).

If you fire a cannon from a mountain top, the shot will eventually hit
the Earth if the initial energy (momentum) is low. It wants to follow a
straight line, but is being accelerated toward the ground, which will
eventually overcome the shot's momentum.

However, if I use more powder, the shot will never hit the ground.
Because of higher momentum, it's new trajectory has the same curvature
as the Earth's surface. It will go into permanent orbit and fall around
the Earth forever. (The equation for the initial Velocity is V =
SQRT(GM/r). Notice that there's only _one_ acceleration term - Gravity.)

That's for circular orbits only.


Now... The Moon is falling around the earth in the same manner, but
it's momentum (its Centrifugal Force) is exactly balanced by the
acceleration of Gravity (its Centripetal Force) and it will orbit the
earth for a very long time.

However........ Because of the effect of the moon's gravitation on the
Earth's tides, the system is losing energy and the Moon is moving away
from the Earth at about 1.5 in/year. The Earth will eventually lose the
moon.

I should note that the system is *not* losing energy (unless one wants
to count gravitational waves). The Earth's rotational energy is being
transmitted to the moon.

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