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Show ALL Forums  > Science/philosophy  > For the theoretical physicists.... Can centripital acceleration be ch      Home login  
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 desertrhino
Joined: 11/30/2007
Msg: 2
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For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?Page 1 of 3    (1, 2, 3)
There is not enough information to answer your question.

Are you talking about turning spin on the craft into linear motion through space?

Give use a little more.
 stargazer1000
Joined: 1/16/2008
Msg: 5
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 12/2/2009 3:22:28 PM
So, basically, like having a weighted string, you swing it around as hard as you can then let go? but once you let go, the acceleration stops.
 AppleGeek
Joined: 9/26/2006
Msg: 6
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For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 12/2/2009 4:16:49 PM
There's no such thing as "centripital acceleration."

When you twirl it over your head your rotating your hand in a circle slightly ahead of the weight. Your applying a linear acceleration to the weight thru the string and the force you exert holding on to the string resists the linear inertial velocity and makes it curve into a circle.

This is the same as the moon except its gravity for a string and its slowing down very slowly.

Now if you were to negate the force of gravity between an object and the earth (and wind resistance) it would travel west and up relative to the ground as the earth continued to turn under it. Touch the top of a ball then slowly turn the ball and move your finder sideways in the same direction at the same time.
 scorpiomover
Joined: 4/19/2007
Msg: 7
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For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 12/2/2009 11:17:45 PM

If that can be figured out, then all that would be needed to travel anywhere is the device that changes centripital acceleration to linear acceleration, powered by a solar panel. Even if the device is only 20% effective in using the solar power it would still provide steady acceleration in the direction it is pointed, and thus slowly increasing the speed of the craft, in addition to providing a slight "gravitaional" force. That would be because it would be constantly accelerating.

A trip to mars would have you accelerating halfway there, then turning the ship around, and decelerating the second half of the trip.................... a nice, liesurely trip.
I think I can see what you mean, if you mean the following:

1) Have a solar panel that absorbs the Sun's solar energy.
2) Use that to make an motor that makes a shaft rotate. Now you have rotating (centripetal) acceleration.
3) Make that rotating shaft somehow converted to drive the craft forwards.

Then you'd have a motor that could produce acceleration in space, powered by the Sun, forever.

Then, as acceleration is the force that hurts, all you would need to do, is use that engine to keep the acceleration constant, but low, so you could have a constant comfortable accelerating halfway to Mars, and a constant decelerating from the halfway point.

I looked up the distance to Mars. At it's farthest, it would be 100 million km away. If the spaceship kept up a steady 0.1g there in a similar manner to what you suggested, I worked out the whole journey to Mars would take: 7 days, 9 hours, 27 minutes, and 56 seconds. About 7 1/2 days. Bear in mind, that's at its farthest distance.

It would be neat if anyone could come up with a drive like this, at least for getting to Mars.
 Island home
Joined: 7/5/2009
Msg: 8
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 12/2/2009 11:47:21 PM
David slayed Goliath with a device that does that didn't he?
 RocketMan_Len
Joined: 7/5/2006
Msg: 9
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 12/3/2009 2:27:41 AM
Paul...

Do a Google search for 'Dean Drive' to see how often this has been tried, and dismissed...
 hyoid
Joined: 5/12/2009
Msg: 10
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 12/3/2009 6:08:28 AM

There's no such thing as "centripital acceleration."


I may be mis-remembering but I thought it was centri-FUGAL acceleration that didn't exist.

Centripetal acceleration is linear-toward the center and exactly canceling that component of momentum which is radial, leaving the tangential component, resulting in a circle.

So
Can centripital acceleration be changed to linear acceleration?


yes. It's called the "wheel".
 scorpiomover
Joined: 4/19/2007
Msg: 13
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For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 12/3/2009 5:23:10 PM
I had another look and it seems like others have also thought along the same lines.
http://en.wikipedia.org/wiki/Reactionless_drive#Oscillation_thruster

Someone called Henry Bull invented one back in 1935. But everyone ignored it, as there was no space program back then.
http://jnaudin.free.fr/html/hbimp35.htm

These drives probably would not be able to develop a lot of acceleration. So I worked out how fast you'd have to go to take 10 years to get to Mars and back. It would require only 0.000,004 m/s^2, or 0.000,000,4g. That's not very much. So it might be possible to generate such a drive to make Mars quite reachable.
 endlesslift
Joined: 12/31/2009
Msg: 19
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/3/2010 10:01:40 PM
Paul,

You need to figure out the difference between the various quantities.

When you swing a weight on a string, there is a centripetal force which causes centripetal acceleration. The centripetal force is not the same thing as centripetal acceleration. (Force is one thing and acceleration is another. They're related but not the same thing).

If you could convert the energy that is stored in a flywheel to linear motion, the energy that is used to create the linear motion is taken away from the flywheel. The flywheel slows down as you take energy away from it.

The wheel is a well known energy that converts energy stored in a rotating object and creates linear motion. You can spin a yoyo and let go of it and it will speed along the ground. But the energy that is changed to forward motion is taken from the spinning of the yoyo. So it slows down. Friction will slow it down too (air friction for example).

So even if there's no friction, the rotating object will slow down as you create linear motion.




OK, I will do the best I can....... When a weight is on the end of a string, and the string is spun in a circle, there is a force that is created called centripital acceleration. Once spinning, it doesn't take much force to keep it spinning. From what I remember of college physics, there was a mathematical way to measure the force created by the weight at the end of the string. Remove friction, as in a vacum, air bearings, and the spinning will go on for very little energy, yet can create quite a bit of energy at the end of the string.

What I am curious about is if that force could somehow be "straightened out" to accelerate in a straight line........ linear...............
.
 JustDukky
Joined: 7/8/2004
Msg: 21
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/4/2010 8:40:32 PM

LINEAR ACCELERATION ......... NO?

Actually, no...The acceleration ends the moment you cut the string. What you are left with is linear motion resulting from the law of inertia.
 jaroka
Joined: 9/21/2009
Msg: 22
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/5/2010 11:07:51 AM
No, centripetal acceleration cannot be changed to linear acceleration.

Reason:

Linear acceleration needs work.

Centripetal acceleration is a process in which no work is expended.

Explanation:

Acceleration of a mass in a linear direction takes energy, because it needs to move the accelerated body out of a "rest" or "constant speed" state. In a continual linear acceleration, this happens continually. To move a resting body out of rest work is needed. Work is force times distance, and the force here is the resistence of the object to accelerate, which is commensurate to the object's mass. In Newtonian mechanics, that force is the mass multiplied by the rate of acceleration. Thus, the work performed is mass, times acceleration, times the distance it is accelerated over.

Acceleration of amass in a circular path does not require work. It is unique situation in acceleration, inasmuch as the force that is exerted to accelerate the object is not in the same direction as the acceleration, but EXACTLY perpendicular to it. Thus, the force is acting, but there is no energy spent. This explains why two cirlcing objects in space, held at a constant distance by gravity, but having no resistence to their movement, will circle each other for ever, without the need to add energy.

Converesely, an object moving on a straight path and not given or taken away any kinetic energy will travel at a constant speed, and no acceleration will take place.
 whwap
Joined: 10/9/2009
Msg: 28
 endlesslift
Joined: 12/31/2009
Msg: 29
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/9/2010 8:03:17 PM
whwap,

sterling engine unrelated to thread.

it's aheat engine.

lift
 Ahron123
Joined: 10/16/2009
Msg: 30
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/10/2010 1:12:02 AM
Your question actually doesn't make any sence.

The motion of an object does not change unless a force acts on it.

When you spin something around on the end of a rope, the object on the end of the rope has LINEAR momentum. If you dont belive me, cut the string! It will move in a linear direction.

The Centrifugal force you talk about is really the sum of an infinate number of linear forces. At any single point, the object is moving linearly with some momentum (that is one force). The force is the rope, which is pulling the object in towards the center. Both of these forces are linear. If you measure them at every point (and there is an infinate number of points) and add all the foces together, you will see why the object moves in a circle.

Oh and if the rope applys a force to the object, the then object applys an equal and opposit force to the rope - that is newtrons third law - and that force is the thing you are calling centrifugal force - it's really the sum of many linear forces :)
 Ahron123
Joined: 10/16/2009
Msg: 34
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/19/2010 7:15:25 AM

Yes, the direction of that force is continually changing, but it's still just one force.


It doesn't matter how you see it. The important thing is that we agree about what is happening. I'm not sure that we do, although we might.

I prefer to think about it my way because it explains why the centrifugal force continues to exist.

I know why it exists. At any ONE point, there is two forces acting on the object. One is the rope, and that's what your calling the centrifugal force; the other is the LINEAR momentum which the object already has. Add those two forces together, and the answer will be the direction that the object actually moves (eg. the net force).

But of course, the object isn't just at one point. The scenario discribed in the previous paragraph happens an infinate number of times as the object orbits. If no friction acts to slow the object down, and if the rope continues to apply the same force, this will continue forever.

I guess really it doesn't matter if you see it an ever changing force or an infinate number of forces...or at least it doesn't matter for any reason that I am aware of.

:)
 insert user name
Joined: 5/4/2006
Msg: 35
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/19/2010 8:45:04 AM
The answer to your question is no, centripital acceleration cannot be changed to linear acceleration.

To put it in laymans terms, once the spinning has ceased and the linear path begins, the object in question will not increase in speed. Assuming you were in a vacuum and you were spinning a rock in a sling at 50 miles per hour, the rocks velocity on release would be 50 mile per hour. A new force would have to be applied to increase its speed, this would be a new force applied as linear acceleration.

So no, a transition like that cannot take place.
 printer2
Joined: 6/19/2007
Msg: 45
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 1/23/2010 5:43:08 PM
You guys make my head hurt.

An object spinning round in an orbit will stay in the same orbit unless energy is added or removed. You can not just take the energy there and change directions. First off, forget the string. Not a good way of looking at things. Think gravity well, and a bed sheet.

Maybe not a bed sheet but a rubber sheet. Stretch it out flat then put something of medium weight on it. It is quite obvious what will happen, the weight is pulled down by gravity and there is a depression in the sheet where your weight is.

Now say you have a marble and you want it to spin around the object on the sheet. You pick yourself an orbit and give it enough energy to spin around the weight. If you have the right amount of energy it will spin around the object, not falling in towards the object and not climbing out of the orbit it is in. If you remove energy it falls in. If you add energy it goes up away from the object making the depression.

Any light bulbs coming on?

Now replace the sheet with space and your weight with the Earth. Now have a space ship orbit the earth. Do you think you can use the energy used to hold it in its orbit to leave its orbit? I hope not.

Now looking a bit further out we have Mars with its own gravitational well distorting space around it. So we have to clime out of our well, move way over there, and then scrub off energy when we go down Mar's well. Does not seem too bad does it?

But hold on, Mars and the Earth are really small, gravitationally speaking. Lets look around and see who is the big Kahuna in the neighborhood. Oh yeah, the Sun. So it is also distorting space and causing the Earth and Mars to spin around it. We are falling down yjr Sun's gravitational well and the only thing stopping us is the momentum we have spinning us round in a circle.

I guess you can also see that since Mars is farther away from the sun than the Earth is that we have to fight our way out of the Sun's gravitational well to get to Mars.

So much for straight line acceleration. I'll leave you there.
 A1_GOLD
Joined: 5/6/2009
Msg: 52
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For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 2/3/2010 6:51:06 PM
You folks have not read enough science fiction.
This guy is talking about an anti-gravity drive.
No f=ma, just the idea that if you snip the force of gravity you will move at a tangent to whatever source of gravity you were being dragged around by.

Theoretically there is no reason that an anti-gravity device couldn't be built but as far as I can tell it requires at least some (c) Beyondrealityite (tm) paint (patent pending). I've heard that a hardware store on Beta Centauri 6 might have a good stock on hand. Each liter bottle sells for 10 kilo of E135 or 100 kilo anti-Iron, they got to make a profit you know.
 Ahron123
Joined: 10/16/2009
Msg: 55
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 3/2/2010 7:11:47 PM

Actually, since I am the one who posed the question, I can say with no uncertainty that the question is not about "anti-gravity".



Ha ha...I'm fairly sure he was making a JOKE. For a start, he began with, "You guys have not read enough science fiction." He then went on to explain the address of a hardware store from which supplies for producing an anti-gravity machine could be purchased. It’s FUNNY :)
 Ahron123
Joined: 10/16/2009
Msg: 57
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 3/4/2010 6:59:51 AM
Paul mate, your off the show ha ha. I don’t have to be clearer about who I address my posts to. You just have to read the posts IN ORDER.

This is what happened:

1.) You posted an opening post, and sparked much discussion. But there was NO MENTION of anti gravity until...
2.) A1_GOLD made a JOKE, in which he mentioned something called anti-gravity.
3.) You responded to A1_GOLD’s post as if it was serious (which it wasn't).
4.) I quoted you, and saying “Actually, since I am the one who posed the question, I can say with no uncertainty that the question is not about anti-gravity", and I responded with a message informing you that I believe A1_GOLD realises that the thread is not about anti-gravity, and I pointed out that I believe A1_GOLD is only making a JOKE.

AS a side point, I happen to think the joke made by A1_GOLD was quite funny :)

Just out of interest, are you autistic or in any way unusual in the way you think? I'm just curious, and I have total respect for whatever the answer may be.


You didn't even have the courtesy to take the time to read my posts


I did read your posts. In fact if you go and read your responses, you will find that early in the thread I even tried to make some contribution. I have to confess though, I am no physics expert.


...otherwise you would see that I never brought up, nor have I discussed anti-gravity, others have.

The first mention of anti-gravity is in message 57, written by A1_GOLD. Once again, he was only JOKING.
 Epicetus
Joined: 2/21/2010
Msg: 59
For the theoretical physicists.... Can centripital acceleration be changed to linear acceleration?
Posted: 3/4/2010 5:09:28 PM
>> changes centripital acceleration to linear acceleration ....

mmh, can of worms
centrifugal force is an acceleration a body must receive to go in a circular motion at the same constant velocity... and that acceleration is towards the centre of spin (causing a continual change of direction, from the inertial straight line to a curved motion)

Centrifugal force is simply inertia.... ie cut the string and inertia says the circularly rotating body will go in a straight line (which happens to be in the forward direction, a tangent to the circle, when the curving force, the centripetal force is removed)

so upon cutting the string, the body has only the linear velocity at that time... no more direction changes, therefore no more acceleration
It travels tangentially and not radially away

so no is the answer to the above Q

But there is something in this..... the so called "bootstrap enigma".... can you lift yourself by your own bootlaces ?
..... see Dean Drive, might give you some clues ... I suspect this is what the OP had in mind ??????
but if I told you the physics, then I would have to kill you.....
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