inertia only applies to travelling in a straight line

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inertia only applies to travelling in a straight line
« on: May 10, 2016, 11:01:23 AM »
You can throw a tennis ball to a friend on a moving train and it will behave as if the train is still.

Now try doing it when the train is going around in a circle, the ball will always end up to the left of where it should have landed.

In physics when something travels in a circular path it's velocity is constantly changing. The object may have a constant speed but it is constantly changing direction to get a circular path.

Going around a corner in a car at a constant speed still makes the passengers move to one side.

So if the earth is circling the sun it's angular velocity should be constantly changing so we should feel it
This ride goes around at a constant speed but the chairs still flare outwards

« Last Edit: May 10, 2016, 12:36:47 PM by Ex-Globe »
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Re: inertia only applies to travelling in a straight line
« Reply #1 on: May 10, 2016, 12:32:29 PM »
You can throw a tennis ball to a friend on a moving train and it will behave as if the train is still.

Now try doing it when the train is going around in a circle, the ball will always end up to the left of where it should have landed.

The ball will always land where it should land; it will land to the left of your initial aim point if the train is turning to the right.

Quote
In physics when something travels in a circular path it's angular velocity is constantly changing. The object may have a constant speed but it is constantly changing direction to get a circular path.

Going around a corner in a car at a constant speed still makes the passengers move to one side.

So if the earth is circling the sun it's angular velocity should be constantly changing so we should feel it

[Note: The following analysis in not correct for this situation and should be ignored. The calculated centripetal acceleration is correct (I think), but it does not apply to the question at hand. The content below is being left here for completeness, but should be disregarded. I apologize for any confusion.]

[IOW... oops!  :-[ ]


How much acceleration is being applied to the Earth to keep it in its orbit? That's straightforward enough to calculate:

a = v2/r

where:
r is the radius of the Earth's orbit; r = 150,000,000 km = 150,000,000,000 m
v is orbital speed; v = circumference of the Earth's orbit / period of the Earth's orbit
 = 2 * pi * r / (365.25 days * 86,400 seconds/day)
 = 942,000,000,000 m / 31,557,600 sec
v = 29,900 m/s [rounded to three digits of precision]

a = (29,900 m/s)2 / 150,000,000,000 m
 = 894,010,000 m2/s2 / 150,000,000,000 m
a = 0.00596 m/s2

How much is the average acceleration of gravity at sea level?

g0 = 9.81 m/sec2

a = 0.0601% of g0

This means the weight of an average-size person weighing 700N at g0 (mass ~ 71.4 kg) would change from 700.42N at noon to 699.58N at midnight due to the acceleration of the Earth moving in its orbit. Would you expect to feel that?
« Last Edit: May 11, 2016, 08:30:06 AM by Alpha2Omega »
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Re: inertia only applies to travelling in a straight line
« Reply #2 on: May 10, 2016, 12:38:48 PM »
There should be an experiment available to measure this if it's real.

Is there?
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Pezevenk

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Re: inertia only applies to travelling in a straight line
« Reply #3 on: May 10, 2016, 12:40:37 PM »
That's a fine answer, but what exactly do you mean by:
"This means the weight of an average-size person weighing 700N at g0 (mass ~ 71.4 kg) would change from 700.42N at noon to 699.58N at midnight due to the acceleration of the Earth moving in its orbit. Would you expect to feel that?"


I don't think it's very clear.
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Re: inertia only applies to travelling in a straight line
« Reply #4 on: May 10, 2016, 12:45:30 PM »
There should be an experiment available to measure this if it's real.

Is there?

There shouldn't be an experiment like that. All it means is that instead of your weight being what it would be if the earth was stationary, it is very slightly less. However, there are measurements of different gravitational accelerations in different parts of the earth (due to the varying densities, distances from the centre and the centrifugal acceleration from the earth's rotation around itself), which the flat earthers of course reject.
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Re: inertia only applies to travelling in a straight line
« Reply #5 on: May 10, 2016, 12:55:44 PM »
He said the weight changes from noon to midnight
There should be an experiment to measure this
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Re: inertia only applies to travelling in a straight line
« Reply #6 on: May 10, 2016, 01:10:25 PM »
You can throw a tennis ball to a friend on a moving train and it will behave as if the train is still.

Now try doing it when the train is going around in a circle, the ball will always end up to the left of where it should have landed.

In physics when something travels in a circular path it's angular velocity is constantly changing. The object may have a constant speed but it is constantly changing direction to get a circular path.

Going around a corner in a car at a constant speed still makes the passengers move to one side.

Yes, we do also have that force applied to us as we orbit the sun.

Quote
So if the earth is circling the sun it's angular velocity should be constantly changing so we should feel it
No.

In your image, the centrifugal force is clearly very great in relation to the very short distance. The centrifugal acceleration experienced by the kids on the carousel, people in the car, and the ball on the train are all influenced by the radius of the turn. Because that turn is relatively sharp, their forward momentum is preserved more by inertia so they exert more force away from the center, so centripetal force (seat for the carousel, seat belts for the car, nothing for the ball) presses just as much.

Their change in momentum is very noticeable because it's very sharp--and they feel it in the pressure provided by the centripetal force's reaction. A physical presence is noticeable; we don't have any object directly pushing us and Earth towards the sun. In addition, if you traveled 100 miles per hour forward and decelerated backwards instantly, your guts would get jerked around everywhere and you very well could die. If it weren't for that tangible and/or particularly sudden physical force, for example the kids being held in by their seats, it wouldn't be noticeable.

And anyway, we have a turning radius of 93 million miles and turn at a speed of 2*pi/365 radians/day. Earth's orbit is hardly sharp or rapid, astronomically speaking. In addition, every part of us is uniformly accelerated in towards the Sun, so not one organ or nerve ending would feel any different regardless of how fast we accelerate.

That's a fine answer, but what exactly do you mean by:
"This means the weight of an average-size person weighing 700N at g0 (mass ~ 71.4 kg) would change from 700.42N at noon to 699.58N at midnight due to the acceleration of the Earth moving in its orbit. Would you expect to feel that?"

I don't think it's very clear.
This is the difference in gravitational force from the Sun depending on whether you're on the side of Earth facing it or facing away.

He said the weight changes from noon to midnight
There should be an experiment to measure this
Read his post. His point is that it's virtually unnoticeable. That's a tenth of a percent increase.
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Re: inertia only applies to travelling in a straight line
« Reply #7 on: May 10, 2016, 01:29:04 PM »
Maybe we can't feel it,but there should be an instrument to measure this difference
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Re: inertia only applies to travelling in a straight line
« Reply #8 on: May 10, 2016, 03:06:01 PM »
Maybe we can't feel it,but there should be an instrument to measure this difference

You mean a scale?

Re: inertia only applies to travelling in a straight line
« Reply #9 on: May 10, 2016, 04:13:16 PM »
Maybe we can't feel it,but there should be an instrument to measure this difference

I believe there are a few problems with the idea of weight changing from night to day. Take the ISS for example, it is orbiting around the Earth in a constant free fall. The astronauts inside the station are also orbiting and in a constant free fall, both the astronauts and the station are accelerating towards the center of the Earth at somewhere around 0.9 G. The astronauts experience weightlessness, you can not weigh yourself on the space station, because they are in constant acceleration.

We are also orbiting the Sun. The Earth can be viewed as our space station, we as astronauts inside the station. We should experience weightlessness with regards to the Sun because we are in a constant free fall towards it.

Re: inertia only applies to travelling in a straight line
« Reply #10 on: May 10, 2016, 05:03:28 PM »
Maybe we can't feel it,but there should be an instrument to measure this difference

I believe there are a few problems with the idea of weight changing from night to day. Take the ISS for example, it is orbiting around the Earth in a constant free fall. The astronauts inside the station are also orbiting and in a constant free fall, both the astronauts and the station are accelerating towards the center of the Earth at somewhere around 0.9 G. The astronauts experience weightlessness, you can not weigh yourself on the space station, because they are in constant acceleration.

We are also orbiting the Sun. The Earth can be viewed as our space station, we as astronauts inside the station. We should experience weightlessness with regards to the Sun because we are in a constant free fall towards it.

That's a good point; I may have taken the wrong approach to the problem - the answer I got, as small as it is, was larger than expected. The intra-day difference may boil down to tidal effects, which, for the Sun, are quite small. Let me think about it. Thanks!

[I added a disclaimer to the original post. Sorry about that. Good catch, Inkey!]
« Last Edit: May 11, 2016, 08:33:31 AM by Alpha2Omega »
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rabinoz

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Re: inertia only applies to travelling in a straight line
« Reply #11 on: May 10, 2016, 10:10:24 PM »
So if the earth is circling the sun it's angular velocity should be constantly changing so we should feel it
Sure, the earth is orbiting the sun, but at an angular velocity of one revolution per year! Big deal.

A much faster rotation is the earth on its axis at one revolution per sidereal day (23.934 hours).
That is a whole 0.0007 rpm!
No, I don't think that you would feel that!

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disputeone

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Re: inertia only applies to travelling in a straight line
« Reply #12 on: May 10, 2016, 11:09:02 PM »
In physics when something travels in a circular path it's velocity is constantly changing. The object may have a constant speed but it is constantly changing direction to get a circular path.

Einstein set it out in GR, a circle is a straight line in curved spacetime caused by mass, that's why gravity is defined as a fictional force
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Re: inertia only applies to travelling in a straight line
« Reply #13 on: May 10, 2016, 11:47:06 PM »
Just because you don't understand something doesn't mean it's not real.
That's a common theme I've found in FET.

I don't understand females but am still pretty sure they exist.
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Re: inertia only applies to travelling in a straight line
« Reply #14 on: May 11, 2016, 12:01:34 AM »
He said the weight changes from noon to midnight
There should be an experiment to measure this

Ah, I just realized what he is talking about! There is an "experiment" to measure this. It's called "tides". What he mentioned is the primary reason tides occur.
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Re: inertia only applies to travelling in a straight line
« Reply #15 on: May 11, 2016, 02:55:19 AM »
I thought tides were due to the moon, not the earth going around the sun.
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Re: inertia only applies to travelling in a straight line
« Reply #16 on: May 11, 2016, 04:24:01 AM »
I thought tides were due to the moon, not the earth going around the sun.

The ocean tides are mostly caused by the moon. The sun does have a tidal relationship with the Earth as well, but it is much smaller than the moons, around 3% of the moons.

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Re: inertia only applies to travelling in a straight line
« Reply #17 on: May 11, 2016, 04:29:27 AM »
I thought tides were due to the moon, not the earth going around the sun.

Inkey is right, the moon has a greater influence on the tides than the sun, but the influence of the sun is still present. The tidal influence of the sun working with that of the moon creates spring tides, while when it works against that of the moon it creates neap tides.
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Re: inertia only applies to travelling in a straight line
« Reply #18 on: May 11, 2016, 07:47:32 AM »
I thought tides were due to the moon, not the earth going around the sun.

The ocean tides are mostly caused by the moon. The sun does have a tidal relationship with the Earth as well, but it is much smaller than the moons, around 3% of the moons.

Clarifying further, the moon itself causes high tides on the side of the earth which is facing it.  The high tides on the side of earth facing away from the sun moon are caused primarily by centrifugal force of the earth-moon system as they revolve around a common center of mass.
« Last Edit: May 11, 2016, 06:56:56 PM by uCantBeSerious »

Re: inertia only applies to travelling in a straight line
« Reply #19 on: May 11, 2016, 09:55:06 AM »
Clarifying further, the moon itself causes high tides on the side of the earth which is facing it.  The high tides on the side of earth facing away from the sun are caused primarily by centrifugal force of the earth-moon system as they revolve around a common center of mass.
The moon's gravity pulls water from the "sides" of the earth towards it, sides meaning neither directly under the moon nor on the other side but around the "horizon" as viewed from the moon. On the opposite side it would be just pulling the water straight into the earth so it won't go anywhere. This, coupled with what uCantBeSerious pointed out, allows for the water on the other side of the moon to remain at high tide.
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Re: inertia only applies to travelling in a straight line
« Reply #20 on: May 11, 2016, 11:50:12 AM »
OK one round earther just said the sun is the primary reason for the tides and another says it's only 3%

How is this measured?

There must be a way of actually measuring the inertia of the earth orbiting the sun with an instrument
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Re: inertia only applies to travelling in a straight line
« Reply #21 on: May 11, 2016, 08:57:37 PM »
OK one round earther just said the sun is the primary reason for the tides

Where? This post? That looks like an erratum. It has been corrected.
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Re: inertia only applies to travelling in a straight line
« Reply #22 on: May 12, 2016, 12:06:58 AM »
So if the earth is circling the sun it's angular velocity should be constantly changing so we should feel it

If you were to stand blind folded on a large Second hand rotating once in one minute i do not think you would be able to feel it.  totally no way for the one minute hand rotating in one hour.    As for the one year hand............................     

>>There must be a way of actually measuring the inertia of the earth orbiting the sun with an instrument

If you want to measure it as a force acting upon the test equipment while the test equipment is rotating once per day and the moon sun and the planets have a tidal effect on Earth I wonder if you can.    Is the force greater than the tide created by jupiter for example?
« Last Edit: May 12, 2016, 12:17:30 AM by Aliveandkicking »

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Pezevenk

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Re: inertia only applies to travelling in a straight line
« Reply #23 on: May 12, 2016, 12:10:44 AM »
OK one round earther just said the sun is the primary reason for the tides and another says it's only 3%

How is this measured?

There must be a way of actually measuring the inertia of the earth orbiting the sun with an instrument

Nobody said the SUN was a primary reason. The EFFECT is the primary reason. The moon also has the same effect on the earth, but on a much larger scale. The basic principles however are the same.
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Re: inertia only applies to travelling in a straight line
« Reply #24 on: May 12, 2016, 12:19:51 AM »
I just realised we cannot detect the force caused by the Earth rotating the Sun because the Earth is always at all times in free fall around the Sun.   We are weightless with respect to the Sun regardless of whatever forces are applied to us by the moon or planets and so forth.

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Re: inertia only applies to travelling in a straight line
« Reply #25 on: May 12, 2016, 01:03:37 AM »
I just realised we cannot detect the force caused by the Earth rotating the Sun because the Earth is always at all times in free fall around the Sun.   We are weightless with respect to the Sun regardless of whatever forces are applied to us by the moon or planets and so forth.
[/quote

You are right, to an extent. We can detect the gradient, because the side of the earth that is closer to the sun is more attracted to it. Same thing with the moon. The opposite happens on the other side. That's what causes the tides. Here's some more information: https://en.m.wikipedia.org/wiki/Tidal_force
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Re: inertia only applies to travelling in a straight line
« Reply #26 on: May 12, 2016, 01:46:27 AM »
I just realised we cannot detect the force caused by the Earth rotating the Sun because the Earth is always at all times in free fall around the Sun.   We are weightless with respect to the Sun regardless of whatever forces are applied to us by the moon or planets and so forth.

You are right, to an extent. We can detect the gradient, because the side of the earth that is closer to the sun is more attracted to it. Same thing with the moon. The opposite happens on the other side. That's what causes the tides. Here's some more information: https://en.m.wikipedia.org/wiki/Tidal_force

I think i am simply right.   We cannot detect the force that is flinging us off to one side, like in a fair ground ride because we are in free fall and by definition there are no detectable forces upon us whatsoever.     Earlier I was thinking about the magnitude of this force and if it would be bigger than the tidal force of jupiter.    I assume we cannot measure the tidal force of jupiter either even though it can be estimated.

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Re: inertia only applies to travelling in a straight line
« Reply #27 on: May 12, 2016, 02:39:06 AM »
I just realised we cannot detect the force caused by the Earth rotating the Sun because the Earth is always at all times in free fall around the Sun.   We are weightless with respect to the Sun regardless of whatever forces are applied to us by the moon or planets and so forth.

You are right, to an extent. We can detect the gradient, because the side of the earth that is closer to the sun is more attracted to it. Same thing with the moon. The opposite happens on the other side. That's what causes the tides. Here's some more information: https://en.m.wikipedia.org/wiki/Tidal_force

I think i am simply right.   We cannot detect the force that is flinging us off to one side, like in a fair ground ride because we are in free fall and by definition there are no detectable forces upon us whatsoever.     Earlier I was thinking about the magnitude of this force and if it would be bigger than the tidal force of jupiter.    I assume we cannot measure the tidal force of jupiter either even though it can be estimated.

I didn't say anything about Jupiter.

Anyway, you'd be right, if the gravitational acceleration didn't depend on the distance, or if we all lived on the centre of mass of the earth. Tidal forces are detectable, just not very powerful. But other than that, you're absolutely right, and it's something that many flat earthers seem to miss.
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Re: inertia only applies to travelling in a straight line
« Reply #28 on: May 12, 2016, 05:01:50 AM »
I just realised we cannot detect the force caused by the Earth rotating the Sun because the Earth is always at all times in free fall around the Sun.   We are weightless with respect to the Sun regardless of whatever forces are applied to us by the moon or planets and so forth.

You are right, to an extent. We can detect the gradient, because the side of the earth that is closer to the sun is more attracted to it. Same thing with the moon. The opposite happens on the other side. That's what causes the tides. Here's some more information: https://en.m.wikipedia.org/wiki/Tidal_force

I think i am simply right.   We cannot detect the force that is flinging us off to one side, like in a fair ground ride because we are in free fall and by definition there are no detectable forces upon us whatsoever.     Earlier I was thinking about the magnitude of this force and if it would be bigger than the tidal force of jupiter.    I assume we cannot measure the tidal force of jupiter either even though it can be estimated.

I didn't say anything about Jupiter.

Anyway, you'd be right, if the gravitational acceleration didn't depend on the distance, or if we all lived on the centre of mass of the earth. Tidal forces are detectable, just not very powerful. But other than that, you're absolutely right, and it's something that many flat earthers seem to miss.

Your answer to the question appears to be, we cannot measure the force your body experiences as Earth orbits the sun once per year,   however going off on a tangent a bit, the Sun does create a tide on earth as Earth rotates about Earths axis once per day which can be measured.   

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Pezevenk

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Re: inertia only applies to travelling in a straight line
« Reply #29 on: May 12, 2016, 05:11:27 AM »
I just realised we cannot detect the force caused by the Earth rotating the Sun because the Earth is always at all times in free fall around the Sun.   We are weightless with respect to the Sun regardless of whatever forces are applied to us by the moon or planets and so forth.

You are right, to an extent. We can detect the gradient, because the side of the earth that is closer to the sun is more attracted to it. Same thing with the moon. The opposite happens on the other side. That's what causes the tides. Here's some more information: https://en.m.wikipedia.org/wiki/Tidal_force

I think i am simply right.   We cannot detect the force that is flinging us off to one side, like in a fair ground ride because we are in free fall and by definition there are no detectable forces upon us whatsoever.     Earlier I was thinking about the magnitude of this force and if it would be bigger than the tidal force of jupiter.    I assume we cannot measure the tidal force of jupiter either even though it can be estimated.

I didn't say anything about Jupiter.

Anyway, you'd be right, if the gravitational acceleration didn't depend on the distance, or if we all lived on the centre of mass of the earth. Tidal forces are detectable, just not very powerful. But other than that, you're absolutely right, and it's something that many flat earthers seem to miss.

Your answer to the question appears to be, we cannot measure the force your body experiences as Earth orbits the sun once per year,   however going off on a tangent a bit, the Sun does create a tide on earth as Earth rotates about Earths axis once per day which can be measured.   

I think we've both misunderstood each other a bit! I did say that the Sun creates a tide, but the reason for that is the stronger gravitational attraction of the sun on the side that is closer to it, together with the centrifugal acceleration of the earth as it revolves around it. That is why the sun and the moon don't create a high tide only on the side of the earth that they're facing, but on the opposite side as well. Don't forget that the moon doesn't revolve around the earth without the earth moving, they both revolve around a common barycenter. It looks kinda like that: https://upload.wikimedia.org/wikipedia/commons/5/59/Orbit3.gif

"Your answer to the question appears to be, we cannot measure the force your body experiences as Earth orbits the sun once per year,"

I'm not sure if I said that or what you mean by that.

Anyway, your point is correct, but we can detect the tidal forces.
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