Space

[lasersailor184]

You can not feel Inertia, you can only see it.


If space was infinite and black, you would not know that you are moving, because you have nothing to judge this off of.

If you're going 60mph down the road, you can tell because the road marks are shooting past really really quickly.


But, thinking about this, I do believe Goob is technically correct.  Inertia is momentum.  

To change inertia (momentum) you need acceleration (either positive or negative).  Therefor, you do not directly feel inertia, but the change in it.

[2bighorn]

Originally posted by g00b
"Question for you. How does above explain your claim: "You do not feel inertia in space"?"

I never claimed inertia is not present or non-existant.

Inertia is NOT a force. How can you feel something that is not a force?


g00b

Acceleration is NOT a force either. How can you feel something that is not a force?

[lasersailor184]

Acceleration IS (basically) a force.  The vital piece of information your missing though, is mass.  Everything has mass, so everything that is accelerating is feeling a force.

[2bighorn]

Originally posted by lasersailor184
Acceleration IS (basically) a force.  The vital piece of information your missing though, is mass.  Everything has mass, so everything that is accelerating is feeling a force.

Acceleration is "the rate of change of velocity of an object with respect to time". It is NOT a force.

To your previous post, and Goob's and why we talk about inertia.

Inertia does not equal momentum. In physics momentum is defined, inertia is not. Inertia (as we know it today) is just descriptive term which contains some of the ingredients necessary to feel G forces in space (that was the original question all about), mass, momentum and acceleration included.

So I will say it again (for the 3rd time): Inertia describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration.

[lasersailor184]

Force = Mass X Acceleration.

[Gh0stFT]

its still beyound me why they dont build rotating space stations,
like "von Braun" suggested, to avoid the problems Humans get
while in space with zero Gravity, and we are now in 2005...

[g00b]

OK, I can't help myself. 1 last time, as simple as possible.

In the big black void of space you can only percieve a CHANGE in velocity, correct? If you disagree here, I am at a loss for any further comment and give up entirely. Remember, velocity = speed AND direction.

To change velocity requires acceleration.

I maintain....

You do not feel inertia in space. Only acceleration.

g00b

GhostFT

It's a good idea, I think the problem is docking. Either you have to spin your dock or your incoming ship to match. Neither is easy and failure is catostophic. Solves alot of problems though.

[lasersailor184]

Everything takes energy.  It would take a lot of energy to get a space station in orbit rotating at the correct velocity to generate earth like acceleration.  


However, the problem is that it would take a lot more energy to keep the Station rotating at the correct velocity.  Like my talks about Center of Gravity.  Anytime a person moves, they throw off the center of gravity, and even the speed of rotation.

Anytime you put a weight in the station, be it even an apple, you change the center of gravity.  The space station would have to adjust for this to keep in perfect rotation.


The real problem is not that we don't know how to do this.  

The real problem is that we don't have an energy source capable of sustaining this.  Rocket Fuel for example, takes up a lot of space, and mass.  It burns a lot just getting the shuttle into space.  Now, the space shuttle doesn't need a lot of rocket fuel to get back to earth because it is basically falling.  You don't need energy to fall.


So until we figure out a super powerful clean compact power source, we're still going to be doing things the same way.

[Chairboy]

Maybe you can help us poor dumb guys by defining exactly what inertia "feels" like on earth, then, so we can understand why you would not "feel" it in space.

[Shane]

Originally posted by Chairboy
Maybe you can help us poor dumb guys by defining exactly what inertia "feels" like on earth, then, so we can understand why you would not "feel" it in space.

very simple.

run full speed into a wall. that point of time between the impact and the brain registering it is inertia.

[g00b]

Originally posted by Chairboy
Maybe you can help us poor dumb guys by defining exactly what inertia "feels" like on earth, then, so we can understand why you would not "feel" it in space.

Maybe you should answer your own question.

How does one feel inertia?

And how can you percieve this WITHOUT acceleration?

Even Shanes glorious illustration of inertia, involves a sudden negative acceleration.

In a stagnant universe with NO acceleration (you could still have inertia) you would never feel anything because nothing would ever change. That's what inertia IS, the tendency to stay the same. I.e. No change.

g00b

[lasersailor184]

Inertia is best described as Momentum.

If you push an object in space it will continue to move on forever at that same exact velocity in that exact same direction (assuming no outside interference).

This is quantified as Mass X Velocity.

However, we on earth have outside interference.  

Say you push a car in Neutral down the hill.  Momentum (inertia) would tell us that it would go on forever, but this is not true.

The car would have friction on the axles slowing down the car.  It will also have Wind Resistance pushing on the front of the car.  Eventually, it will come to a stop somewhere down the road.

Like I said before, if you were in a car going 60, you would know.  You can look out the window and see the trees moving past.  You have some good guess as to how fast you are going, but your speedometer tells you exactly.

But when you are in the car, you feel nothing (disregard bumps in the road).  If you were to close your eyes and sit still you would not know that you are actually moving.  Movement can only be percieved.


Now, however, acceleration with respect to momentum is different.  You can feel it when the driver steps on the pedal.  Say you accelerate from a dead stop.  You have 0 momentum because you have 0 velocity.  When the car accelerates, you feel yourself pushed against the back of the seat.

When the car stops, you feel yourself pushed against the seatbelts.

Again, if you were to close your eyes and not hear the car (or the bumps in the road), you would feel yourself accelerate.  You would feel yourself get pushed against the back of the car, and you would say to yourself, "Hmm, we are speeding up."

If you close your eyes and you feel yourself pushing against the seatbelt, you would say to yourself, "Hmm, we are slowing down."


So goob is correct.

[Chairboy]

No, goob is not correct.  What you are feeling on earth is not inertia, you're feeling the acceleration imposed by the various forms of drag around you (air, water, gravity, friction, etc).

Goob keeps using this word inertia...  but I do not think it means what he thinks it means.

Lasersailor, when you're in a stopped car on Earth, you are not at 0 velocity.  On one frame, you are moving at a little over 1,000 mph as the planet rotates.  On another frame, you're moving around the sun at about 66,000 mph.  The sun is orbiting the center of the galaxy at about 560,000 mph.  The Milky Way is travelling at about a million miles per hour towards the Virgo supercluster, but at this point, it's awful tricky to figure out what these speeds are relative to, so, it's best to just not think about it.



To answer the original question of this thread, you would feel pushed down/red out stresses on pitchover in space if you were far from the center of mass, but if you were sitting in the middle, it would be a slight rocking sensation at best.

[2bighorn]

Originally posted by lasersailor184
Force = Mass X Acceleration.

your previous claim was: Acceleration = Force which is incorrect.

Originally posted by lasersailor184
So goob is correct.

He claims inertia is nonexistent in space. This is incorrect. He claims (and so do you) that you feel acceleration.

I say you feel (have) inertia (in space) whenever there's change in motion.

Change in motion involves acceleration, but is only one part of it.

I'll say it again for the 4th time: Inertia (in space) describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration.

So, why would that be wrong and what makes your claim more precise or better?

It's like I'm pointing to a tree saying:"It's tree"
You're pointing out leaf and saying:"Not true, it's a branch, leaf is a proof I'm right."

Besides, with every post your "theory" changes.

[g00b]

Originally posted by 2bighorn


He claims inertia is nonexistent in space. This is incorrect. He claims (and so do you) that you feel acceleration.

Nowhere do I claim inertia is nonexistant. As a matter of fact I clarify after your 1st falsity "I never claimed inertia is not present or non-existant." Your insisting I have claimed inertia is non-existant TWICE now, when I have never done so shows that you are either not reading my posts, or are simply making up your own facts as we go along.

My orignal apparently contentious statement was:

You do not feel inertia in space. Only acceleration.

I do not see ANY valid proofs presented by you or chairboy to the contrary.

Your statement "Inertia (in space) describes resistance of an object with mass to change of motion. Change of motion is simply change of velocity or change of motion's direction ie acceleration and/or angular acceleration." only strengthens my arguement as it is based upon the pre-requisite of acceration.

Inertia incorporates acceleration into it's very definition.

I really need to stop replying to this thread.

g00b