A noob and his gravity.

Quote from: Gulliver on June 18, 2007, 09:24:59 PM

Let's back up. Tell me the difference between constant velocity and constant acceleration. Then consider playing ping-pong on a train moving with constant velocity. Then with constant acceleration. Think about what happens when the train decelerates quickly. Think about what happens when the train makes a sharp curve (without load-balancing trucks or graded track). You feel acceleration.

When the train de-accelerates, the force of friction from the brakes pulling it backwards while inertia tries to move it forward, putting structural stress on the train. Most of the train is iron and steel and very structurally sound. The cabin containing us and the ping pong table isn't. When we turn a curve we are likewise trying to break inertia, which wants us to keep going straight. This is what happens when there are conflicting forces. However, if we are in a room that is magically and suddenly lifted at a high velocity into the air, and we presume there is no gravity or counteracting force, we have no such conflict of forces.

Okay. Let's try again after your kind correction. First I must point out that you haven't answered my request, emphasized above. Please do so. It will help.

Next let's see if we agree on the following. You can't play a normal game of ping-pong of a train that is accelerating. (In physics, accelerating mean increasing speed, decreasing speed, changing direction, or some combination.)

The room might be aboard a spacecraft far from the influence of a planet's gravity. The acceleration up might come from a rocket engine pushing up under the floor of the room. Just like in the plane when you're pushed back during the acceleration of take-off, you'll feel the effect. No magic is required. In the room, you'll stay still until something comes along to push you, and that'll be the floor.

A quick off topic question about mass Vs. weight: If you were to say and objects mass were 10Kg,  would this be simply its weight at one G? If not, what then. Thanks.

A quick off topic question about mass Vs. weight: If you were to say and objects mass were 10Kg,  would this be simply its weight at one G? If not, what then. Thanks.

Nope.... F=ma; a=g=9.81m/s² down; m=10kg; F=(10Kg)(9.81m/s²)= 98.1N down.

(Just type this "10kg * g in newtons" into your Google search bar and get the answer for the cool kids over at Google.)

Let's take this a step at a time.  You have a mass of 10kg.  How do you find how much it weighs?

I would check how strongly it is pulled downwards towards the Earth relative to a known weight on some sort of scale.

I didn't say anything about an argument, I said discussion.

No, you misunderstand. I wasn't referring to what form the discussion was taking; I was pointing out that your blustering does not equal a counter-argument. If you think I am mistaken about something, point it out; otherwise, you're simply avoiding the question.

Okay. Let's try again after your kind correction. First I must point out that you haven't answered my request, emphasized above. Please do so. It will help.

Constant velocity is a stable rate of change in displacement. Constant acceleration is a stable rate of change in the rate of change of displacement.

The acceleration up might come from a rocket engine pushing up under the floor of the room. Just like in the plane when you're pushed back during the acceleration of take-off, you'll feel the effect. No magic is required. In the room, you'll stay still until something comes along to push you, and that'll be the floor.

I've actually brushed back up on this, and yes, I was wrong about acceleration. However, it remains true that if all matter is being moved simultaneously in one direction, no displacement is taking place. If this room, and I inside it, are the only things in the Universe, then such a question becomes moot. It is impossible for the room to move.

Accelerating against something?  I'm not sure what you mean.  When you are accelerating in a car what are you accelerating against?

Against the street.

It's just another dude confusing the properties of acceleration and velocity. Or possible the effects of the UA.

Or wondering why the acceleration of the Earth doesn't cause the Sun and Moon to crash down on top of Europe.

Actually, I already corrected that mistake. However, it's true that the rate of change in the rate of change in the distance between two points depends upon there actually being a second point.

Quote from: Gulliver on June 18, 2007, 11:31:38 PM

Okay. Let's try again after your kind correction. First I must point out that you haven't answered my request, emphasized above. Please do so. It will help.

Constant velocity is a stable rate of change in displacement. Constant acceleration is a stable rate of change in the rate of change of displacement.

Quote

The acceleration up might come from a rocket engine pushing up under the floor of the room. Just like in the plane when you're pushed back during the acceleration of take-off, you'll feel the effect. No magic is required. In the room, you'll stay still until something comes along to push you, and that'll be the floor.

I've actually brushed back up on this, and yes, I was wrong about acceleration. However, it remains true that if all matter is being moved simultaneously in one direction, no displacement is taking place. If this room, and I inside it, are the only things in the Universe, then such a question becomes moot. It is impossible for the room to move.

Joe, I thank you for reconsidering. I believe you show strength of character.

Let's move on to the question whether displacement is taking place. Let's visit the Law of the Conservation of Momentum. This Law states that in all interactions, no net momentum is created or lost.

Imagine that you find yourself adrift about 100 yards or so from your spacecraft all alone in deep space. You and your spaceship have the same velocity, so you're not moving towards or away from the spacecraft. You can't remove anything from suit except for the oxygen tank holding the last of your breathable air. You have no hope of rescue, as your spouse on the spacecraft is soundly asleep, again. What do you do?

Well, you can't swim back, as there is nothing to swim against, such as water. The answer is: You must remove your oxygen tank and throw it directly away from the craft. You need momentum towards the craft. You can't create momentum, but you can redistribute it. If you give some object momentum away from the craft, you'll get momentum toward the craft. Then hold your breath, you can bang of the craft and wake your spouse to rescue you. (You might also enter an airlock on your own, and let your spouse sleep.)

That's a lot to handle in one post. Please read over this a second time. Ask me any questions you have about this concept, then we'll move on. (It's going to take about 10 posts for me to explain all of this, so please be patient.) 

I understand the example, but aside from being in space, it's more or less normal movement.

The scenario in the FE model seems, at first, to be quite different. All the known matter in the Universe is moving at exactly the same speed upwards. In effect, I believe we can treat this as one body.

A closer comparison would be you floating in deep space, with an internal oxygen tank you can't remove. Let's say you can't even remove the suit by yourself. There's not another physical object within any measurable distance of you, just empty, dark space. How do you move? Your relationship to any point can't change, as you're the only point. There's nothing to push against or pull towards, or be pulled towards, and no way of telling if you're moving at all.

Of course, this seems wrong to me now, as my current understanding is that FE theory holds that some energy source on the bottom of the Earth is pushing away from the Earth and causing it to travel "upward" at an exactly even acceleration, and has presumably been doing so for all of known time, so all of the matter/energy in this Universe is not moving all together in the same direction. But this raises a lot of questions of it's own- what is this energy source? Does it have infinite fuel (and how is that supposed to work), or are we going to run out soon, at which point we'll all fly off up into the Sun? And if the mass of the Earth and the associated bodies with it is decreasing, shouldn't the rate of acceleration be increasing as the mass of the body it's moving decreases? Shouldn't we be going a truly ludicrously large number of lightyears per second relative to the energy left behind when we first started this journey?

Although all this seems less relevant than the fact that I just watched a sunrise, and the Sun was not tiny and speck like as a bird or cloud or car disappearing in the distance, but about it's normal size and revealing itself in fractions over the horizon.

...
Although all this seems less relevant than the fact that I just watched a sunrise, and the Sun was not tiny and speck like as a bird or cloud or car disappearing in the distance, but about it's normal size and revealing itself in fractions over the horizon.

You're right on track there. It's Experiment 1 in the RE Primer. Good job.

I understand the example, but aside from being in space, it's more or less normal movement.

The scenario in the FE model seems, at first, to be quite different. All the known matter in the Universe is moving at exactly the same speed upwards. In effect, I believe we can treat this as one body.

A closer comparison would be you floating in deep space, with an internal oxygen tank you can't remove. Let's say you can't even remove the suit by yourself. There's not another physical object within any measurable distance of you, just empty, dark space. How do you move? Your relationship to any point can't change, as you're the only point. There's nothing to push against or pull towards, or be pulled towards, and no way of telling if you're moving at all.

Of course, this seems wrong to me now, as my current understanding is that FE theory holds that some energy source on the bottom of the Earth is pushing away from the Earth and causing it to travel "upward" at an exactly even acceleration, and has presumably been doing so for all of known time, so all of the matter/energy in this Universe is not moving all together in the same direction. But this raises a lot of questions of it's own- what is this energy source? Does it have infinite fuel (and how is that supposed to work), or are we going to run out soon, at which point we'll all fly off up into the Sun? And if the mass of the Earth and the associated bodies with it is decreasing, shouldn't the rate of acceleration be increasing as the mass of the body it's moving decreases? Shouldn't we be going a truly ludicrously large number of lightyears per second relative to the energy left behind when we first started this journey?

...

Wow! You're right on track with your comments. You see that Law of Conservation of Momentum means that the UA has to be throwing oxygen tanks down to maintain the FE's acceleration up. You see there is something not just left behind, but also flying away from us. Think about that and I believe that you'll find the FE has a lot of explaining to do regarding its constant acceleration for billions of years. (Like where is it getting of all those oxygen tanks?)

You raise many good challenges to FE. I suggest that you look for threads (use the search feature) that discuss that challenge and post what you can contribute on that challenge there. And whenever you see (or post) something that should be in the RE Primer, post a pointer in the thread in my signature line below. Welcome to the RE Team and thanks.