How much of an inverse impact is the earth rotation on gravity?

[Beau]

Does the earth rotation act as an opposing force to the gravity created by its mass? if so how much. And if it does, wouldn't it mean that objects of equal mass would have a different weight if one was on the equator (location of greatest centrifugal force) and the other on one of the poles (no centrifugal force).

Also, if it does make a difference, wouldn't it also be true that since the moon is what keeps the earth spinning at a constant rate, and since it is slowly moving away from us, that as the moon moves away, the earth's spin would slow, and gravity would increase?

further, if all of the above is correct, wouldn't it make all living creatures evolve to shorter heights over time?

I really have no clue what I'm talking about, but I watched a program on the discovery channel and it got me thinking (uh-oh)...

Edit:

This page seems to support my theory.

-k- this has the math and theory I was looking for.... question answered

 

[edro]

I think gravity is less on the moon because it is not rotating... or maybe it's because it is really small.... I dunno.

 

[Beau]

Originally posted by: edro13
I think gravity is less on the moon because it is not rotating... or maybe it's because it is really small.... I dunno.

Not talking about gravity on the moon... I'm talking about gravity on earth.

 

[Amused]

Originally posted by: edro13
I think gravity is less on the moon because it is not rotating... or maybe it's because it is really small.... I dunno.

I weep for our education system.

 

[Heisenberg]

What do you mean by "opposes"? You mean the rotation would tend to fling things off the surface while gravity holds them down?

 

[wfbberzerker]

i'm pretty sure there is no effect on the gravity at all, primarily because the forces are on different axes(sp?). gravity creates a force going down, while the rotation, which would cause an object to have inertia, would be at an angle perpendicular to gravity.

 

[edro]

Originally posted by: Amused

Originally posted by: edro13
I think gravity is less on the moon because it is not rotating... or maybe it's because it is really small.... I dunno.

I weep for our education system.

Well then enlighten us....

 

[Beau]

Originally posted by: wfbberzerker
i'm pretty sure there is no effect on the gravity at all, primarily because the forces are on different axes(sp?). gravity creates a force going down, while the rotation, which would cause an object to have inertia, would be at an angle perpendicular to gravity.

Isn't gravity is a centripetal force (from what I understand, a force going toward the center of a circular motion)? the rotational inertia would create a centrifugal force (opposite of centripetal?) and would negate it.

 

[edro]

Yep, it's because it's really small. See... I told ya.

 

[Ameesh]

Originally posted by: edro13

Originally posted by: Amused

Originally posted by: edro13
I think gravity is less on the moon because it is not rotating... or maybe it's because it is really small.... I dunno.

I weep for our education system.

Well then enlighten us....

NEWTON'S LAW OF GRAVITY
The ATTRACTIVE FORCE OF GRAVITY IS DIRECTLY PROPORTIONAL TO THE
PRODUCT OF THE MASSES AND INVERSELY PROPORTIONAL TO THE
SQUARE OF THE DISTANCE BETWEEN THEM.

or

F = G m_1 m_2 / d^2

where G = 6.673 x 10^{-11} m^3 kg^-1 s^-2
Combine with his SECOND LAW OF MOTION:
the ACCELERATION DUE TO GRAVITY OF AN OBJECT IS PROPORTIONAL
TO ITS MASS AND INVERSELY PROPORTIONAL TO THE
SQUARE OF THE DISTANCE FROM ITS CENTER.


a = F/m
Here we call the acceleration due to gravity, g and
g = F_grav/m_2 = G m_1 m_2 / (d^2 m_2)
g = G m_1 / d^2

Example: if m_1 = M_E(arth) and d = R_E we have
g = [6.673 x 10^{-11} m^3 kg^-1 s^-2] [5.974 x 10^{24} kg] / (6.378 x 10^6 m)^2
g = 9.80 m s^{-2} (or 32 ft/s^2)
YOU SHOULD VERIFY THIS CALCULATION!
Weight is the force due to gravity acting on a mass (amount of matter)
so W = m g (special case of F = m a).

Since gravity gets weaker a greater distances, you actually
weigh less at the top of a building than you do at its base,
even though your mass hasn't changed.
Since Atlanta is about 300 m above sea level, you weigh a little less here
than you would in Savannah -- at sea level, and closer to the center of the earth.
You weigh more in an elevator as it just accelerates to go up
and less in one that acclerates to go down and
you are weightless in one that is falling w/o support!

Newton figured this out by comparing the acceleration the Moon feels
compared to that felt at the surface of the Earth.

He knew the distance from Earth to Moon was about 60 x R_E
He computed the inertial ("centripetal") acceleration due to rotation
(as determined from experiments -- like rock swung on string)
a = v^2 / d
Start from v_M = circumference of orbit/period of orbit, or
v_M = 2 pi d_EM / P = = 2 pi 3.84 x 10^8 m / (27.32 d x 24 x 60 x 60)
or v_M= 1.02 km s^-1
This gives,
a_Moon = 2.7 x 10^-3 m s^-2
Newton realized that a_M = g/(3625) = g/(d_EM/R_E)^2

and concluded that the INVERSE SQUARE RELATION OF GRAVITY
ON DISTANCE was likely to be true EVERYWHERE.

 

[Beau]

Originally posted by: edro13
Yep, it's because it's really small. See... I told ya.

Are you dumb?

I'm not asking about the moons gravity.

 

[Heisenberg]

The gravity of an object is proportional to its mass. The reason the moon has less gravity is because it's smaller. Gravity is what keeps everything on the face of the planet. Without it, the rotational motion of the planet would tend to fling things off in a straight line, at a tangent to the rotation. Gravity provides the centripetal force to keep everything stationary, so to speak.

 

[edro]

Well no crap... I was using it as an example....

 

[Beau]

Originally posted by: edro13
Well no crap... I was using it as an example....

An example of what? I don't see how it applies.

 

[Beau]

Originally posted by: Heisenberg
The gravity of an object is proportional to its mass. The reason the moon has less gravity is because it's smaller. Gravity is what keeps everything on the face of the planet. Without it, the rotational motion of the planet would tend to fling things off in a straight line, at a tangent to the rotation. Gravity provides the centripetal force to keep everything stationary, so to speak.

Well right, but that would also equate to saying if the earth had no rotation, gravity would be greater because there'd be no opposing force trying to throw things off the surface

 

[Heisenberg]

Originally posted by: Beau

Originally posted by: Heisenberg
The gravity of an object is proportional to its mass. The reason the moon has less gravity is because it's smaller. Gravity is what keeps everything on the face of the planet. Without it, the rotational motion of the planet would tend to fling things off in a straight line, at a tangent to the rotation. Gravity provides the centripetal force to keep everything stationary, so to speak.

Well right, but that would also equate to saying if the earth had no rotation, gravity would be greater because there'd be no opposing force trying to throw things off the surface

The force of gravity would remain the same. The net force felt by objects would change.

 

[edro]

Originally posted by: Beau

Originally posted by: edro13
Well no crap... I was using it as an example....

An example of what? I don't see how it applies.

There is gravity on the moon, but it is a lot less.... yet you do not fly off the moon when there is no rotation.... Therefore, the centrifigal force is prolly a lot less than gravity.

 

[Beau]

Originally posted by: edro13

Originally posted by: Beau

Originally posted by: edro13
Well no crap... I was using it as an example....

An example of what? I don't see how it applies.

There is gravity on the moon, but it is a lot less.... yet you do not fly off the moon when there is no rotation.... Therefore, the centrifigal force is prolly a lot less than gravity.

Of course you wouldn't fly off the moon when there is no rotation. Rotation is what would make you fly off the moon. Absence of it would just keep things in tighter.

 

[Iron Woode]

Originally posted by: Beau

Originally posted by: wfbberzerker
i'm pretty sure there is no effect on the gravity at all, primarily because the forces are on different axes(sp?). gravity creates a force going down, while the rotation, which would cause an object to have inertia, would be at an angle perpendicular to gravity.

Isn't gravity is a centripetal force (from what I understand, a force going toward the center of a circular motion)? the rotational inertia would create a centrifugal force (opposite of centripetal?) and would negate it.

LOL.

You can't even spell, let alone understand basic physics.

Ok I will make this simple:

Gravity is not caused by a rotating body. Gravity is a curvature of the space-time continuim caused by the mass of an object. Gravity acts equally at all parts of the globe, drawing objects to the earth's center at a constant rate of acceleration. Whether the object weighs an ounce or 10 tonnes or if you have 2 different weighted objects, they all accelerate at the same rate to the ground.

Inertia is the tendancy of an object to continue doing what it is doing. In other words if an object is still, then it will stay still until some force acts upon it.

Just what are you trying to get at? The earth's rotation is caused by its formation. The rate of rotation is slowing down, not due to gravity, but, due to the drag of our atmosphere and the tug of our moon. In the past a day may have been 16 hours long and one day the earth will just stop rotating.

 

[Iron Woode]

Originally posted by: edro13

Originally posted by: Beau

Originally posted by: edro13
Well no crap... I was using it as an example....

An example of what? I don't see how it applies.

There is gravity on the moon, but it is a lot less.... yet you do not fly off the moon when there is no rotation.... Therefore, the centrifigal force is prolly a lot less than gravity.

The moon rotates on its axis. This is basic astronomy.

 

[Amused]

Originally posted by: edro13

Originally posted by: Amused

Originally posted by: edro13
I think gravity is less on the moon because it is not rotating... or maybe it's because it is really small.... I dunno.

I weep for our education system.

Well then enlighten us....

The amount of gravity is due to the amount of mass. The higher the mass, the stronger the gravity. The moon has less gravity because it has less mass.

This is 7th grade remedial science here.

 

[Beau]

Originally posted by: Iron Woode


You can't even spell, let alone understand basic physics.

Ok I will make this simple:

Gravity is not caused by a rotating body. Gravity is a curvature of the space-time continuim caused by the mass of an object. Gravity acts equally at all parts of the globe, drawing objects to the earth's center at a constant rate of acceleration. Whether the object weighs an ounce or 10 tonnes or if you have 2 different weighted objects, they all accelerate at the same rate to the ground.

Inertia is the tendancy of an object to continue doing what it is doing. In other words if an object is still, then it will stay still until some force acts upon it.

Just what are you trying to get at? The earth's rotation is caused by its formation. The rate of rotation is slowing down, not due to gravity, but, due to the drag of our atmosphere and the tug of our moon. In the past a day may have been 16 hoursllong and one day the earth will just stop rotating.

I didn't say gravity was caused by a rotating body. I know what gravity is.

Re-read the first post. I may have gotten my terms wrong, but the idea is still there. I'm simply wondering how much of an opposing force the earth rotation plays to gravity. Gravity being the force created by earth's mass, causing other objects to fall to it's center. The earths rotation (without gravity) would be cause objects to fly off the surface, so it must act as an anti-gravity force to a certain degree. If it does, then wouldn't it play more of an opposing force to gravity at the earths equator than at the poles?

 

[Haircut]

a = rw^2

where r = radius of Earth ~ 6.3 * 10^6 m
w = angular velocity = 2*pi / (86400) ( 1 rotation every day)

therefore a = 0.003 m/s^2

acceleration due to gravity is ~ 9.81 m/s^2 so it will be offset very slightly at the equator, not enough to make a difference to anything though.

As an aside, here is an interesting page about the gravity on Earth
http://news.bbc.co.uk/1/hi/sci/tech/3093927.stm

 

[Beau]

Originally posted by: Haircut
a = rw^2

where r = radius of Earth ~ 6.3 * 10^6 m
w = angular velocity = 2*pi / (86400) ( 1 rotation every day)

therefore a = 0.003 m/s^2

acceleration due to gravity is ~ 9.81 m/s^2 so it will be offset very slightly at the equator, not enough to make a difference to anything though.

As an aside, here is an interesting page about the gravity on Earth
http://news.bbc.co.uk/1/hi/sci/tech/3093927.stm

Thank you. That's what I was looking for

 

[Iron Woode]

Originally posted by: Beau

Originally posted by: Iron Woode


You can't even spell, let alone understand basic physics.

Ok I will make this simple:

Gravity is not caused by a rotating body. Gravity is a curvature of the space-time continuim caused by the mass of an object. Gravity acts equally at all parts of the globe, drawing objects to the earth's center at a constant rate of acceleration. Whether the object weighs an ounce or 10 tonnes or if you have 2 different weighted objects, they all accelerate at the same rate to the ground.

Inertia is the tendancy of an object to continue doing what it is doing. In other words if an object is still, then it will stay still until some force acts upon it.

Just what are you trying to get at? The earth's rotation is caused by its formation. The rate of rotation is slowing down, not due to gravity, but, due to the drag of our atmosphere and the tug of our moon. In the past a day may have been 16 hoursllong and one day the earth will just stop rotating.

I didn't say gravity was caused by a rotating body. I know what gravity is.

Re-read the first post. I may have gotten my terms wrong, but the idea is still there. I'm simply wondering how much of an opposing force the earth rotation plays to gravity. Gravity being the force created by earth's mass, causing other objects to fall to it's center. The earths rotation (without gravity) would be cause objects to fly off the surface, so it must act as an anti-gravity force to a certain degree. If it does, then wouldn't it play more of an opposing force to gravity at the earths equator than at the poles?

I think what you are asking is :

Can the rotational force of the earth have a cancelling effect on gravity at different places on the earth?

Is this correct?