Gravity 1 & Gravity 2

[griffithsuk]

It doesn't.

 

It must else it would not return to its start point. The further out you go the faster it spins with the planet above it's start point, as it does.

Edited May 12, 2011 by griffithsuk

[Cap'n Refsmmat]

It must else it would not return to its start point. The further out you go the faster it spins with the planet above it's start point, as it does.

 

It doesn't return to its start point, as it happens.

[griffithsuk]

It doesn't return to its start point, as it happens.

 

we would have terrible weather then.

 

and if i threw a ball up then it would land somewhere else.

 

None of this is true, im sure of this.

 

if i shot a gun directly up in the air with no wind, the bullet would return exactly back down the barrel in "perfect theory".

Edited May 12, 2011 by griffithsuk

[Cap'n Refsmmat]

we would have terrible weather then.

Our atmosphere isn't being launched straight upwards in a rocket very often.

 

The thing that throws the rocket off is the vertical motion. If you had a rocket hover an inch above the ground, it'd land at almost exactly the same spot it started at.

[griffithsuk]

Our atmosphere isn't being launched straight upwards in a rocket very often.

 

The thing that throws the rocket off is the vertical motion. If you had a rocket hover an inch above the ground, it'd land at almost exactly the same spot it started at.

 

im quite sure anything you shoot up returns exactly to its start point. Gravity pulls down and also drags around.

 

Aas I said, Double wammy! gravity must drag else there would be a problem with people walking with/in the space station, it's not friction.

 

Night all.

Edited May 12, 2011 by griffithsuk

[Schrödinger's hat]

we would have terrible weather then.

and if i threw a ball up then it would land somewhere else.

None of this is true, im sure of this.

if i shot a gun directly up in the air with no wind, the bullet would return exactly back down the barrel in "perfect theory".

One of the reasons we get things like cyclones and the reason air and water currents act the way they do is the coriolis effect.

If you shoot a gun or throw a ball high enough it does come back in a different place. The best way of illustrating the physics involved in this effect is the

.

The reason you think that a ball or a bullet will come straight back down is that the earth is very very big, and so you can't throw a ball very high compared to its radius.

 

With regard to your rocket experiment, I'm not quite sure how to explain orbital mechanics in a way that won't confuse the issue further.

I think the best thing would be to think about

for a while. A good example is Neptune's moon Triton.

 

Another thing to understand is circular motion. (that and the next two videos).

Then we can start discussing gravity.

[griffithsuk]

One of the reasons we get things like cyclones and the reason air and water currents act the way they do is the coriolis effect.

If you shoot a gun or throw a ball high enough it does come back in a different place. The best way of illustrating the physics involved in this effect is the

.

The reason you think that a ball or a bullet will come straight back down is that the earth is very very big, and so you can't throw a ball very high compared to its radius.

 

With regard to your rocket experiment, I'm not quite sure how to explain orbital mechanics in a way that won't confuse the issue further.

I think the best thing would be to think about

for a while. A good example is Neptune's moon Triton.

 

Another thing to understand is circular motion. (that and the next two videos).

Then we can start discussing gravity.

 

thank you.

 

Not sure though. gravity must drag else there would be a problem with people walking with/in the space station, it's not friction.

Edited May 12, 2011 by griffithsuk

[Schrödinger's hat]

I don't know what you mean by 'it's not friction', but I'll try to explain anyway. (watch the videos on centripetal acceleration, they will help a lot)

 

Say someone is sitting in the middle of the space station or the shuttle or whatever not touching anything, why don't they hit the wall? (let's ignore

Well the person and the space station were accelerated to the same speed originally by a rocket, so if there was no gravity or anything else accelerating them they could sit there just fine without bumping into anything.

 

But gravity is accelerating them.

It just so happens that there is the same force per unit mass on them as the space station. So they have the same acceleration.

That means they will always be moving at the same speed as the space station.

 

Watch the video, or find a book to read about circular motion if you want to know why moving in one direction, and accelerating at a right angle (what gravity does to something in a circular orbit -- elliptical orbits are a slightly more complicated version of the same thing) makes you go in a circle at constant speed.

 

Or come on the chat and ask.

[Klaynos]

im quite sure anything you shoot up returns exactly to its start point. Gravity pulls down and also drags around.

 

Just because you're quite sure doesn't mean you're right. The distance missed depends on the height reached, the time at that height and the speed it took to reach that height.

[ajb]

I have a newer theory, if you fly out to space, after a few miles you float in your spaceship once you leave the pull of earths gravity, so theres little/zero gravity in space, but yet the moon which is 200,000 times further away goes simply around.

 

It was one Newton's great contributions to science to realise that what holds us down on the Earth is the same thing that is responsible for planetary orbits. Newtonian gravity gives nice explanations of the orbits.

 

You have noticed that gravity is a relatively weak force, but it is the most dominant on astrophysical scales.

[swansont]

True, modern theory is it will spin forever(might not be true though, we may slow down due to anything yet not known)

 

 

so your saying that air is orbiting the earth?

 

and an object to maintain an orbit with earth needs to be at the same rotation speed as earth? lets pretend theres is or is not air as this does not matter, correct?

 

A final answer I need is this:

 

I have a rocket, i shoot streight up, im still spining around with the planet. I fly towards the sun. Sometime later Im somewhere between the gravity of the sun and earth, im in limbo. I carry on im now in the pull of the suns gravity.

A. Do I start to spin with the sun? and if turn around back towards the earth, i will start to spin with the earth?

 

Or

 

B. Do i not start to spin with the sun? and if turn around back towards the earth, i will not start to spin with the earth?

 

If it's 'A' then gravity drags, else if it's 'B' then im just wasting peoples time on this one.

 

Option B.

[griffithsuk]

If spining produces gravity, can a person walk on the ceiing of a space station?

[imatfaal]

If spining produces gravity, can a person walk on the ceiing of a space station?

 

Thats why the sci-fi films have the space stations of the future as enormous doughnut shapes. If the doughnut is spinning, in the rim you would feel as if there was gravity towards the outer edge - at the hub one would be weightless.

[griffithsuk]

Thats why the sci-fi films have the space stations of the future as enormous doughnut shapes. If the doughnut is spinning, in the rim you would feel as if there was gravity towards the outer edge - at the hub one would be weightless.

 

Thnks but can you walk on the ceiling.

[imatfaal]

I would define the floor as what I walk upon - so perhaps not. But you can potentially walk normally on the inside surface of the outer rim - and you can call that what you will.

[griffithsuk]

I would define the floor as what I walk upon - so perhaps not. But you can potentially walk normally on the inside surface of the outer rim - and you can call that what you will.

 

so they walk on the outer rim anyway? thats how it works?

[Klaynos]

Also, that's not gravity, just something that seems like gravity.

[griffithsuk]

Also, that's not gravity, just something that seems like gravity.

 

I was thinking that too.Same as spining a bucket full of water around.

Edited May 13, 2011 by griffithsuk

[swansont]

If spining produces gravity, can a person walk on the ceiing of a space station?

 

Spinning doesn't produce gravity.

 

However, the equivalence principle tells us that gravity is indistinguishable from any other acceleration.

 

 

Quick question — by any chance are you Paul G. Griffiths, the inventor?

[griffithsuk]

Spinning doesn't produce gravity.

 

However, the equivalence principle tells us that gravity is indistinguishable from any other acceleration.

 

 

Quick question — by any chance are you Paul G. Griffiths, the inventor?

 

yea, petrol lifting tech.

 

Spinning does not produce gravity? I thought it did, what am i playing with then?

[swansont]

yea, petrol lifting tech.

 

Spinning does not produce gravity? I thought it did, what am i playing with then?

 

!

Moderator Note

I have no idea what you are playing with. Given that you have not increased your understanding of gravity since you were last here, I suspect trolling. No matter. Sockpuppetry is not permitted.

[dumber]

Im rewriting what I said.

 

What feels strange though is the rocket on earth is at the rotation speed of the planet, when i fly off why would the rotation speed of the rocket increase to stay directly above its start point as I get further out?

 

In fact the rotation speed of the rocket must decrease on return. Something to think about too.

 

Does anyone understand what im on about here? Not only is it accelating outwards it's accelerating around too. It's got to go around faster to keep up and stay above the start point.

 

Don't know how I came out with this one.

 

So strange? Who added maths to the universe? Feels mathmatic and not natural. Could be proof of a "God-Made" Universe? I just don't know on this one?

 

Is this the worlds first proof of a possible god?

night all.

Edited May 15, 2011 by dumber

[Janus]

Im rewriting what I said.

 

What feels strange though is the rocket on earth is at the rotation speed of the planet, when i fly off why would the rotation speed of the rocket increase to stay directly above its start point as I get further out?

 

In fact the rotation speed of the rocket must decrease on return. Something to think about too.

 

Does anyone understand what im on about here? Not only is it accelating outwards it's accelerating around too. It's got to go around faster to keep up and stay above the start point.

 

Don't know how I came out with this one.

 

So strange? Who added maths to the universe? Feels mathmatic and not natural. Could be proof of a "God-Made" Universe? I just don't know on this one?

 

Is this the worlds first proof of a possible god?

night all.

 

The rocket will not stay over the same spot. As it rises, it will drift Westward with respect as seen by someone on the surface. Its trajectory will be determined by its initial "Eastward" velocity and its velocity upwards and will be independent of the Earth. This is something that became important to the big guns used as early as WWI. The long range of these guns meant that you had to correct for this effect. When fired, the path of the projectile would appear to curve with respect to the Surface of the Earth.

[dumber]

The rocket will not stay over the same spot. As it rises, it will drift Westward with respect as seen by someone on the surface. Its trajectory will be determined by its initial "Eastward" velocity and its velocity upwards and will be independent of the Earth. This is something that became important to the big guns used as early as WWI. The long range of these guns meant that you had to correct for this effect. When fired, the path of the projectile would appear to curve with respect to the Surface of the Earth.

 

If I fire a rocket 1 mile directly up, about how far does it go to the west?

 

All I knows is If I jump, I go streight up,.

Ive worked out though, that to go streight up my rotation speed must be increasing.

 

I understand taking the curve of the earth in to consideration, but are you saying that my rotation speed does not increase?

 

The earth is 12000 miles wide, so on earth my rotation speed is 12000 * PI.

If I fly up 12000 miles them Im guessing that my rotation speed is 36000 * PI.

Is this true? Or is my rotation speed still 12000 * PI?

Edited May 15, 2011 by dumber

[John Cuthber]

Some people may believe your ideas, but that just proves you can fool some of the people all of the time.

There's no evidence supporting your ideas.

If you fly a balloon long enough and high enough it gets caught up in the jet stream which is caused (in part) by the Coriolis effect. So, it doesn't go straight up and down as you think.

You are simply wrong.

There is no "sideways" component to gravity.

 

(Edit (this is a reply to an earlier comment made by Griffiths uk- sorry for any confusion)

Edited May 15, 2011 by John Cuthber