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Science Forum Index » Astronomy Forum » Why do earth not Fall on Sun?
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Message |
| Raghar |
 Posted: Mon Apr 28, 2008 10:41 am |
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On Apr 27, 9:53 am, Sanny <softta...@hotmail.com> wrote:
Quote: 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?
Let A = (0,0)
Let B = (10,0)
Let va = (0,1)
Let u = A-B
Let u' = A-B/(A-B) DOT (A-B)
Let a = 4*u'/(u DOT u)
va2 = va + a
A2 = A + va2
va2 = 0,1 + 4/100,0
A2 = 0,0 + 4/100,0
Continue with va3, and A3 until you get the idea. |
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| Mike |
| Posted: Mon Apr 28, 2008 10:49 am |
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Guest
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On Apr 28, 1:28 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: slus...@lw4u.com> wrote in message
news:d688ac5d-6b1f-4f83-9dc7-85a5864e816e@r66g2000hsg.googlegroups.com...
On Apr 28, 1:31 am, "Mark Earnest" <gmearn...@yahoo.com> wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:IicRj.139584$yE1.99344@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:2TbRj.139551$yE1.94807@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:jdaRj.139437$yE1.67749@attbi_s21...
Mark Earnest wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
Whoops! The force (gravity) is directed toward the sun and hence the
acceleration is directed toward the sun.
Whoops yourself. If the acceleration was all toward the Sun, the
planet would fall into the Sun, just as the OP perceives.
It is the right angel acceleration that keeps the planet from falling
into the Sun.
See:http://honolulu.hawaii.edu/distance/sci122/Programs/p16/p162.gif
That is fine, except it leaves out the acceleration perpendicular to
the
acceleration
toward the star.
Recommend you get yourself a freshman physics book and do
some self education. Best of luck.
I've already taken that class and made an A.- Hide quoted text -
- Show quoted text -
I believe Sam was referring to the fact that while there is a
*velocity* component in the direction tangent to the orbit, the
acceleration (change in velocity) is directed toward the center of the
star.
*****I agree that modern science backs you up, but respectfully, that makes
no sense at all.
*****There are only two pulls on an orbitting planet: the pull toward the
Sun, of constant acceleration, and the pull at right angles to the direction
of the Sun, also one of constant acceleration.
One force cannot produce two accelerations, look up Newton's second
law, the acceleration is always directed along the line of the
application of force.
There is only on eforce on earth, that of the pull by the sun
(according to Newtonian Mechanics of course). That force is equal to
F = m(g)a = GMmr/|r|^3 here mg is the intertial mass of the earth, M
and m are the gravitational masses of the sun and erath respectively
and r the position vector and |r| the magnidute of that vector.
Since the equivalence principle has been shown to hold to at least one
part in a few trillion, this reduces to:
a = GMr/|r|^3
and the acceleration a is along the vector r as the equation shows.
In order for the planet to remain in orbit, the work done by the
gravitational force must be zero. This means: F dor dr = 0 or mdv/dt
dot dr = 0 or
dv dot dr/dt = 0, which means that changes in velocity, that is dv,
must be orthogonal to velocity dr/dr.
Thus, if earth has an orbital speed of exactly the right amount
perpendicular to acceleration, then it is maintained in orbit. But it
does by empirical observation, so it stays in orbit.
Mike
Quote:
*****If it were any other way, the planet would indeed fall into the Sun.- Hide quoted text -
- Show quoted text - |
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| Mike |
| Posted: Mon Apr 28, 2008 11:24 am |
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Guest
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On Apr 28, 5:12 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: ***It is not one force, it is two forces: (1) the force of constant
acceleration from the gravity of the Sun, and (2) the perpendicular force of
constant accleration that occurs to any object in space which moves quickly
enough.
These two forces ballance each other, and keep the planet from spiraling
into the Sun.
Cannot balance. Think about it: if you have two forces at right
angles, the resultant force points somewhere along the direction of
the path. That would mean that the planet accelerates along its's path
according to F = ma. Which is not the case.
So whoever said that and you, is no more than an empirical idiot.
You cannot deny simple vector addiction, can you? Further you cannot
deny Newton's law, can you? If you do let me know.
If you do not deny vector addition and Newton's second law, then you
should reconsider.
Mike |
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| Mark Earnest |
| Posted: Mon Apr 28, 2008 12:28 pm |
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Guest
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<sluster@lw4u.com> wrote in message
news:d688ac5d-6b1f-4f83-9dc7-85a5864e816e@r66g2000hsg.googlegroups.com...
On Apr 28, 1:31 am, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: "Sam Wormley" <sworml...@mchsi.com> wrote in message
news:IicRj.139584$yE1.99344@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:2TbRj.139551$yE1.94807@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:jdaRj.139437$yE1.67749@attbi_s21...
Mark Earnest wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
Whoops! The force (gravity) is directed toward the sun and hence the
acceleration is directed toward the sun.
Whoops yourself. If the acceleration was all toward the Sun, the
planet would fall into the Sun, just as the OP perceives.
It is the right angel acceleration that keeps the planet from falling
into the Sun.
See:http://honolulu.hawaii.edu/distance/sci122/Programs/p16/p162.gif
That is fine, except it leaves out the acceleration perpendicular to
the
acceleration
toward the star.
Recommend you get yourself a freshman physics book and do
some self education. Best of luck.
I've already taken that class and made an A.- Hide quoted text -
- Show quoted text -
I believe Sam was referring to the fact that while there is a
*velocity* component in the direction tangent to the orbit, the
acceleration (change in velocity) is directed toward the center of the
star.
*****I agree that modern science backs you up, but respectfully, that makes
no sense at all.
*****There are only two pulls on an orbitting planet: the pull toward the
Sun, of constant acceleration, and the pull at right angles to the direction
of the Sun, also one of constant acceleration.
*****If it were any other way, the planet would indeed fall into the Sun. |
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| Mike |
| Posted: Mon Apr 28, 2008 12:36 pm |
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Guest
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On Apr 28, 6:27 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: "Mike" <elea...@yahoo.gr> wrote in message
news:c0819e1b-ad62-4f62-959b-3ba541d0b9eb@59g2000hsb.googlegroups.com...
On Apr 28, 5:12 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
***It is not one force, it is two forces: (1) the force of constant
acceleration from the gravity of the Sun, and (2) the perpendicular force
of
constant accleration that occurs to any object in space which moves
quickly
enough.
These two forces ballance each other, and keep the planet from spiraling
into the Sun.
Cannot balance.
****If it doen't ballance, the either the planet will spiral out into space,
or spiral into the Sun.
*****Not only does it ballance, but it is a perfect ballance.
Think about it: if you have two forces at right
angles, the resultant force points somewhere along the direction of
the path. That would mean that the planet accelerates along its's path
according to F = ma. Which is not the case.
So whoever said that and you, is no more than an empirical idiot.
You cannot deny simple vector addiction, can you? Further you cannot
deny Newton's law, can you? If you do let me know.
If you do not deny vector addition and Newton's second law, then you
should reconsider.
*****I do not consider any law that prevent us from pioneering space.
To outlaw voyages into the Cosmos is the completely of idiocy, to me.
Tell that to your esteemed colleagues.
On the contrary, what you claim makes voyages in space impossible.
Satellites do not need a thruster to keep then in orbit if they get
the right orbital speed at the right height (potential energy). What
you think is happening would make satellites an impossible task.
I will not call you a troll because I think you are just a very
confused person about simple mechanics but I recommend you not ignore
empirical evidence.
So long
Mike |
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| Abo |
| Posted: Mon Apr 28, 2008 1:14 pm |
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Guest
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Sanny wrote:
Quote: When Sun and Earth are attracting each other why do Earth not fall on
Sun.
It would, given enough time.
--
Abo |
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| Richo |
| Posted: Mon Apr 28, 2008 1:55 pm |
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Guest
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On Apr 28, 11:49 am, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: The Earth does not fall into the Sun because it is constantly accelerating
at a right angle to the Sun.
No. The earth does not fall into the sun because of its momentum - a
very large mass travelling at a very high velocity - it tends to keep
moving in a straight line - it doesnt move in a straight line because
a force (gravity pulls it towards the center of the sun. The earth is
falling towards the center of the sun and it falls forever and this
keeps it orbiting.
Tie a rock to a piece of string and whirl it about your head - it
travells in a circle because the string pulls it in towards the center
of the circle - if the string breaks the rock would fly off at a
tangent to the circle - its momentum causes it to continue in a
straight line.
That is what Sir Isaac Newton figured out >300 years ago.
Mark. |
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| Richo |
| Posted: Mon Apr 28, 2008 2:04 pm |
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Guest
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On Apr 28, 1:15 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: "Sam Wormley" <sworml...@mchsi.com> wrote in message
news:jdaRj.139437$yE1.67749@attbi_s21...
Mark Earnest wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
Whoops! The force (gravity) is directed toward the sun and hence the
acceleration is directed toward the sun.
Whoops yourself. If the acceleration was all toward the Sun, the planet
would fall into the Sun, just as the OP perceives.
The Earth does fall towards the center of the sun - continuously.
It has been falling towards the center of the sun for 4.5 billion
years now.
It never gets any closer because of its tangential velocity - earths
momentum wants to move the earth in a straight line - the acceleration
of gravity pulls it off course constantly and makes the earth move in
a circle (an ellipse really but lets keep it simple).
If gods hand reached down and stopped the earths motion - and then let
go the earth would slowly move towards the center of the sun getting
faster and faster - if gods hand reached down and gave the earth a
sideways push - it would fall into orbit.
The orbit is the place where the tangential motion is exactly balanced
by the inward acceleration.
Quote: It is the right angel acceleration that keeps the planet from falling into
the Sun.
Not acceleration - constant speed - momentum.
The acceleration towards the sun balances the tangential momentum -
thats what defines the orbit. move the earth further from the sun it
would have to move slower - move it closer to the sun it would have to
move faster.
Mark. |
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| Mark Earnest |
| Posted: Mon Apr 28, 2008 3:11 pm |
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Guest
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<sluster@lw4u.com> wrote in message
news:641ef325-d0c3-4e9a-bcad-591598be5353@m36g2000hse.googlegroups.com...
On Apr 28, 1:28 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: slus...@lw4u.com> wrote in message
news:d688ac5d-6b1f-4f83-9dc7-85a5864e816e@r66g2000hsg.googlegroups.com...
On Apr 28, 1:31 am, "Mark Earnest" <gmearn...@yahoo.com> wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:IicRj.139584$yE1.99344@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:2TbRj.139551$yE1.94807@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:jdaRj.139437$yE1.67749@attbi_s21...
Mark Earnest wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
Whoops! The force (gravity) is directed toward the sun and hence
the
acceleration is directed toward the sun.
Whoops yourself. If the acceleration was all toward the Sun, the
planet would fall into the Sun, just as the OP perceives.
It is the right angel acceleration that keeps the planet from
falling
into the Sun.
See:http://honolulu.hawaii.edu/distance/sci122/Programs/p16/p162.gif
That is fine, except it leaves out the acceleration perpendicular to
the
acceleration
toward the star.
Recommend you get yourself a freshman physics book and do
some self education. Best of luck.
I've already taken that class and made an A.- Hide quoted text -
- Show quoted text -
I believe Sam was referring to the fact that while there is a
*velocity* component in the direction tangent to the orbit, the
acceleration (change in velocity) is directed toward the center of the
star.
*****I agree that modern science backs you up, but respectfully, that
makes
no sense at all.
*****There are only two pulls on an orbitting planet: the pull toward the
Sun, of constant acceleration, and the pull at right angles to the
direction
of the Sun, also one of constant acceleration.
*****If it were any other way, the planet would indeed fall into the Sun.-
Hide quoted text -
- Show quoted text -
Hi Mark,
So what is it that is "pulling" in the direction right angles to the
sun?
The same thing that is pulling the planet toward the Sun: a force of
constant acceleration.
You have to admit, that the gravitational pull of a Sun upon a planet is one
of constant acceleration.
So it has to be counterballanced by another pull of constant acceleration,
away from the Sun, or the planet will just spiral into the Sun.
I know that this goes against science, but here is some incentive to trying
to understand it: if you succeed in understanding the phenomena of constant
acceleration in space, we will be able to easily travel to the stars and
beyond.
As others have mentioned (in paraphrase) if you were on the moon and
shot a cannonball parallel to the ground, it would travel for awhile
in that direction, while also falling toward the Moon due to
gravitational acceleration. Eventually it hits the ground.
Now, shoot the cannonball out faster. It goes quite a bit farther
before still eventually falling and hitting the ground.
Shoot it out even faster yet, and it goes so far that even as it
falls, the surface of the round Moon is curving away from it
noticeably. It is only being accelerated (pulled) toward the center
of the Moon, but it has enough starting velocity so that it might
travel all the way to the other side of the Moon before hitting the
ground.
Finally, with an even faster shot, it travels all the way around the
Moon and hits the back of the cannon. Or, if you move the cannon, it
keeps traveling around the Moon, in orbit, still with only its initial
velocity, and the only pull coming from the Moon, toward its center.
Spencer |
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| Mark Earnest |
| Posted: Mon Apr 28, 2008 4:12 pm |
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Guest
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"Mike" <eleatis@yahoo.gr> wrote in message
news:250d1284-00c1-4176-a2de-4dcfeb31ba34@t54g2000hsg.googlegroups.com...
On Apr 28, 1:28 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: slus...@lw4u.com> wrote in message
news:d688ac5d-6b1f-4f83-9dc7-85a5864e816e@r66g2000hsg.googlegroups.com...
On Apr 28, 1:31 am, "Mark Earnest" <gmearn...@yahoo.com> wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:IicRj.139584$yE1.99344@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:2TbRj.139551$yE1.94807@attbi_s21...
Mark Earnest wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:jdaRj.139437$yE1.67749@attbi_s21...
Mark Earnest wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
Whoops! The force (gravity) is directed toward the sun and hence
the
acceleration is directed toward the sun.
Whoops yourself. If the acceleration was all toward the Sun, the
planet would fall into the Sun, just as the OP perceives.
It is the right angel acceleration that keeps the planet from
falling
into the Sun.
See:http://honolulu.hawaii.edu/distance/sci122/Programs/p16/p162.gif
That is fine, except it leaves out the acceleration perpendicular to
the
acceleration
toward the star.
Recommend you get yourself a freshman physics book and do
some self education. Best of luck.
I've already taken that class and made an A.- Hide quoted text -
- Show quoted text -
I believe Sam was referring to the fact that while there is a
*velocity* component in the direction tangent to the orbit, the
acceleration (change in velocity) is directed toward the center of the
star.
*****I agree that modern science backs you up, but respectfully, that
makes
no sense at all.
*****There are only two pulls on an orbitting planet: the pull toward the
Sun, of constant acceleration, and the pull at right angles to the
direction
of the Sun, also one of constant acceleration.
One force cannot produce two accelerations, look up Newton's second
law, the acceleration is always directed along the line of the
application of force.
***It is not one force, it is two forces: (1) the force of constant
acceleration from the gravity of the Sun, and (2) the perpendicular force of
constant accleration that occurs to any object in space which moves quickly
enough.
These two forces ballance each other, and keep the planet from spiraling
into the Sun.
There is only on eforce on earth, that of the pull by the sun
(according to Newtonian Mechanics of course). That force is equal to
F = m(g)a = GMmr/|r|^3 here mg is the intertial mass of the earth, M
and m are the gravitational masses of the sun and erath respectively
and r the position vector and |r| the magnidute of that vector.
Since the equivalence principle has been shown to hold to at least one
part in a few trillion, this reduces to:
a = GMr/|r|^3
and the acceleration a is along the vector r as the equation shows.
In order for the planet to remain in orbit, the work done by the
gravitational force must be zero. This means: F dor dr = 0 or mdv/dt
dot dr = 0 or
dv dot dr/dt = 0, which means that changes in velocity, that is dv,
must be orthogonal to velocity dr/dr.
Thus, if earth has an orbital speed of exactly the right amount
perpendicular to acceleration, then it is maintained in orbit. But it
does by empirical observation, so it stays in orbit.
Mike
Quote:
*****If it were any other way, the planet would indeed fall into the Sun.-
Hide quoted text -
- Show quoted text - |
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| Mark Earnest |
| Posted: Mon Apr 28, 2008 5:27 pm |
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Guest
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"Mike" <eleatis@yahoo.gr> wrote in message
news:c0819e1b-ad62-4f62-959b-3ba541d0b9eb@59g2000hsb.googlegroups.com...
On Apr 28, 5:12 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: ***It is not one force, it is two forces: (1) the force of constant
acceleration from the gravity of the Sun, and (2) the perpendicular force
of
constant accleration that occurs to any object in space which moves
quickly
enough.
These two forces ballance each other, and keep the planet from spiraling
into the Sun.
Cannot balance.
****If it doen't ballance, the either the planet will spiral out into space,
or spiral into the Sun.
*****Not only does it ballance, but it is a perfect ballance.
Think about it: if you have two forces at right
angles, the resultant force points somewhere along the direction of
the path. That would mean that the planet accelerates along its's path
according to F = ma. Which is not the case.
So whoever said that and you, is no more than an empirical idiot.
You cannot deny simple vector addiction, can you? Further you cannot
deny Newton's law, can you? If you do let me know.
If you do not deny vector addition and Newton's second law, then you
should reconsider.
*****I do not consider any law that prevent us from pioneering space.
To outlaw voyages into the Cosmos is the completely of idiocy, to me.
Tell that to your esteemed colleagues. |
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| Mark Earnest |
| Posted: Mon Apr 28, 2008 5:53 pm |
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Guest
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"Mike" <eleatis@yahoo.gr> wrote in message
news:a8473c7a-2c61-4d56-a7d4-b46cc365c0ab@l42g2000hsc.googlegroups.com...
On Apr 28, 6:27 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: "Mike" <elea...@yahoo.gr> wrote in message
news:c0819e1b-ad62-4f62-959b-3ba541d0b9eb@59g2000hsb.googlegroups.com...
On Apr 28, 5:12 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
***It is not one force, it is two forces: (1) the force of constant
acceleration from the gravity of the Sun, and (2) the perpendicular
force
of
constant accleration that occurs to any object in space which moves
quickly
enough.
These two forces ballance each other, and keep the planet from spiraling
into the Sun.
Cannot balance.
****If it doen't ballance, the either the planet will spiral out into
space,
or spiral into the Sun.
*****Not only does it ballance, but it is a perfect ballance.
Think about it: if you have two forces at right
angles, the resultant force points somewhere along the direction of
the path. That would mean that the planet accelerates along its's path
according to F = ma. Which is not the case.
So whoever said that and you, is no more than an empirical idiot.
You cannot deny simple vector addiction, can you? Further you cannot
deny Newton's law, can you? If you do let me know.
If you do not deny vector addition and Newton's second law, then you
should reconsider.
*****I do not consider any law that prevent us from pioneering space.
To outlaw voyages into the Cosmos is the completely of idiocy, to me.
Tell that to your esteemed colleagues.
On the contrary, what you claim makes voyages in space impossible.
*****Not at all. If planets need perpendicular constant acceleration to
keep from falling into the Sun, then constant acceleration is a law of
mechanics in movement through the interstellar medium.
*****And if there is constant accereration through the interstellar medium
for objects which go fast enough (therefore breaking apart from the space
fabric), then a rocket from Earth accelerated sufficiently enough would tend
to accelerate until the fastest possible velocity in the universe has been
reached.
****What makes it happen? Well, what makes the constant acceleration effect
of an object falling to Earth? The answer to both: no one knows.
*****Give it a break. We have been stuck in Earth orbit for the last 39
years
since landing a man on the Moon. It is time we re-callibrated our
science engines a bit.
Satellites do not need a thruster to keep then in orbit if they get
the right orbital speed at the right height (potential energy). What
you think is happening would make satellites an impossible task.
I will not call you a troll because I think you are just a very
confused person about simple mechanics but I recommend you not ignore
empirical evidence.
So long.
*****Don't stay gone long. Don't forget to write. |
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| Mark Earnest |
| Posted: Mon Apr 28, 2008 7:54 pm |
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Guest
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"Richo" <m.richardson61@gmail.com> wrote in message
news:a6e91e59-7622-4f1b-b262-a5725bcded36@n1g2000prb.googlegroups.com...
Quote: On Apr 28, 1:15 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:jdaRj.139437$yE1.67749@attbi_s21...
Mark Earnest wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
Whoops! The force (gravity) is directed toward the sun and hence the
acceleration is directed toward the sun.
Whoops yourself. If the acceleration was all toward the Sun, the planet
would fall into the Sun, just as the OP perceives.
The Earth does fall towards the center of the sun - continuously.
It has been falling towards the center of the sun for 4.5 billion
years now.
It never gets any closer because of its tangential velocity - earths
momentum wants to move the earth in a straight line - the acceleration
of gravity pulls it off course constantly and makes the earth move in
a circle (an ellipse really but lets keep it simple).
If gods hand reached down and stopped the earths motion - and then let
go the earth would slowly move towards the center of the sun getting
faster and faster - if gods hand reached down and gave the earth a
sideways push - it would fall into orbit.
The orbit is the place where the tangential motion is exactly balanced
by the inward acceleration.
It is the right angel acceleration that keeps the planet from falling
into
the Sun.
Not acceleration - constant speed - momentum.
It has to be acceleration, otherwise there is no ballance for the
accelerating force of gravity from the Sun.
If God's hand really were in this--and it could be--and he mysteriously
somehow made the Sun wink out of existence, The Earth would continue in the
same line it was in at the disappearance, but would continue to
accelerate...and accelerate...and accelerate...until it reached the fastests
of all possible velocities.
What happens next would be anybody's guess.
It would probably wind up coming to a rest somewhere around the universe's
exterior.
Quote: The acceleration towards the sun balances the tangential momentum -
thats what defines the orbit. move the earth further from the sun it
would have to move slower - move it closer to the sun it would have to
move faster.
Mark.
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| Mark Earnest |
| Posted: Mon Apr 28, 2008 7:56 pm |
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"Richo" <m.richardson61@gmail.com> wrote in message
news:a61cc55b-ded1-4673-91fd-463ca1004c45@s33g2000pri.googlegroups.com...
Quote: On Apr 28, 11:49 am, "Mark Earnest" <gmearn...@yahoo.com> wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
No. The earth does not fall into the sun because of its momentum - a
very large mass travelling at a very high velocity - it tends to keep
moving in a straight line - it doesnt move in a straight line because
a force (gravity pulls it towards the center of the sun. The earth is
falling towards the center of the sun and it falls forever and this
keeps it orbiting.
Tie a rock to a piece of string and whirl it about your head - it
travells in a circle because the string pulls it in towards the center
of the circle - if the string breaks the rock would fly off at a
tangent to the circle - its momentum causes it to continue in a
straight line.
That is what Sir Isaac Newton figured out >300 years ago.
It has also been 39 years since we landed a man on the Moon, and here
we are still monkeying around in Earth orbit.
We need some updating of our rules, iow. |
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| Richo |
| Posted: Mon Apr 28, 2008 9:50 pm |
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On Apr 29, 10:54 am, "Mark Earnest" <gmearn...@yahoo.com> wrote:
Quote: "Richo" <m.richardso...@gmail.com> wrote in message
news:a6e91e59-7622-4f1b-b262-a5725bcded36@n1g2000prb.googlegroups.com...
On Apr 28, 1:15 pm, "Mark Earnest" <gmearn...@yahoo.com> wrote:
"Sam Wormley" <sworml...@mchsi.com> wrote in message
news:jdaRj.139437$yE1.67749@attbi_s21...
Mark Earnest wrote:
The Earth does not fall into the Sun because it is constantly
accelerating
at a right angle to the Sun.
Whoops! The force (gravity) is directed toward the sun and hence the
acceleration is directed toward the sun.
Whoops yourself. If the acceleration was all toward the Sun, the planet
would fall into the Sun, just as the OP perceives.
The Earth does fall towards the center of the sun - continuously.
It has been falling towards the center of the sun for 4.5 billion
years now.
It never gets any closer because of its tangential velocity - earths
momentum wants to move the earth in a straight line - the acceleration
of gravity pulls it off course constantly and makes the earth move in
a circle (an ellipse really but lets keep it simple).
If gods hand reached down and stopped the earths motion - and then let
go the earth would slowly move towards the center of the sun getting
faster and faster - if gods hand reached down and gave the earth a
sideways push - it would fall into orbit.
The orbit is the place where the tangential motion is exactly balanced
by the inward acceleration.
It is the right angel acceleration that keeps the planet from falling
into
the Sun.
Not acceleration - constant speed - momentum.
It has to be acceleration, otherwise there is no ballance for the
accelerating force of gravity from the Sun.
The suns gravity pulls the earth towards it - what pulls the earth
"sideways"?
There is no such force - there is momentum and there is the force of
gravity.
Together they guarantee that the planets orbit in an ellipse.
Satelites orbit the earth without having to constantly fire their
rockets.
If they do fire their rockets to increase their tangential velocity
they go into a higher orbit.
If something pushed the earth sideways it would move into a higher
orbit.
If something retarded its sideways motion it would fall to a lower
orbit.
If there is Zero sideways acceleration - it will orbit at the same
distance from the Sun forever.
Any change in velocity is an acceleration - if you draw the vectors
the *change* in velocity is directed towards the center of the circle.
the *change* in velocity in the tangential direction is zero, none.
http://en.wikipedia.org/wiki/Centripetal_force
Quote:
If God's hand really were in this--and it could be--and he mysteriously
somehow made the Sun wink out of existence, The Earth would continue in the
same line it was in at the disappearance, but would continue to
accelerate...and accelerate...and accelerate...until it reached the fastests
of all possible velocities.
No - to accelerate it needs a force - there is no tangential force -
if the sun winked out of existence the earth would continue on at a
constant velocity.
Please don't argue with this - I am not trying to fool you - I am not
lying.
I am trying to teach you something - for free!
(I do have a degree in physics by the way - normally I would charge
for tuition)
You just need to think carefully about the fact that acceleration
needs a force - staying at a constant velocity is just momentum.
I think you can do this Mark - i have faith ! - just think about that
rock on a string whirling about your head - the only two things going
on are a central force (acceleration inwards) and momentum.
Mark. |
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