Dinosaurs and gravitational pull

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BOGWarrior89

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Dinosaurs and gravitational pull
« Reply #60 on: January 16, 2007, 07:11:44 PM »
Quote from: "Big Giant Head"
Quote from: "weevil"
BogWarrior89  we just got off that BORING argument and now you are starting up again! Big Square Head was trying to establish another discussion.
Dont pontificate!


Thank you Weevil.  

Just to clarify Boggy...

Centrifugal force (from Latin centrum "center" and fugere "to flee") is a term which may refer to two different forces which are related to rotation. Both of them are oriented away from the axis of rotation, but the object on which they are exerted differs.

A real or "reactive" centrifugal force occurs in reaction to a centripetal acceleration acting on a mass. This centrifugal force is equal in magnitude to the centripetal force, directed away from the center of rotation, and is exerted by the rotating object upon the object which imposes the centripetal acceleration. Although this sense was used by Isaac Newton, it is only occasionally used in modern discussions.
A pseudo or "fictitious" centrifugal force appears when a rotating reference frame is used for analysis. The (true) frame acceleration is substituted by a (fictitious) centrifugal force that is exerted on all objects, and directed away from the axis of rotation.
Both of the above can be easily observed in action for a passenger riding in a car. If a car swerves around a corner, a passenger's body seems to move towards the outer edge of the car and then pushes against the door.

In the reference frame that is rotating together with the car (a model which those inside the car will often find natural), it looks as if a force is pushing the passenger away from the center of the bend. This is a fictitious force, not an actual force exerted by some other object. The illusion occurs when the reference frame is the car, because that ignores the car's acceleration. A number of physicists treat it much as if it were a real force, as they find that it makes calculations simpler and gives correct results.

Considered fictitious or phantom does not quantify its non-existence.  

You goose.

Back on topic now if we please...
Nyah.


Guess what?  Wikipedia can be wrong, and this time it is.  Here, what you should have read when you clicked on that link I gave you:
Quote from: "I"
There is merely an illusion of a force pulling you outward.

Consider this diagram:



Now, velocity changes because the object is moving in a circle (hence the "circular motion" part), which is depicted in this diagram:



Now, if the centripetal force were to no longer force you into circular motion, you'd fly off in a straight line and at a constant velocity, as is shown here:



So, centrifugal force is not a real force.


F = m * a.  The force is equal to the mass of the object acted upon multiplied by the acceleration the object is undergoing.  Acceleration is the time derivative of velocity, and the second time derivative of position.

Hope that clears that up, and for good.

Dinosaurs and gravitational pull
« Reply #61 on: January 16, 2007, 07:35:28 PM »
Bogwarrior,

It does exist in one form or another, just because it is considered to be false does not mean we don't experience it.  What you're saying though relies on centripedal force being taken out of the equation - which isn't going to happen so it looks like you can't have one without the other - supposedly phantom or not.  Guess that's why they call it a 'phenomenon'.
e fail English? That's unpossible!

Believing is seeing the things which we don't believe we're seeing.... or something like that.

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BOGWarrior89

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Dinosaurs and gravitational pull
« Reply #62 on: January 16, 2007, 07:59:30 PM »
Quote from: "Big Giant Head"
Bogwarrior,

It does exist in one form or another, just because it is considered to be false does not mean we don't experience it.  What you're saying though relies on centripedal force being taken out of the equation - which isn't going to happen so it looks like you can't have one without the other - supposedly phantom or not.  Guess that's why they call it a 'phenomenon'.


It isn't a force, so therefore "centrifugal force" doesn't exist.

You obviously know very little about the mechanics of rotational motion.

Dinosaurs and gravitational pull
« Reply #63 on: January 16, 2007, 08:10:20 PM »
I see what you're saying bogwarrior and I stand corrected (yes, I do admit if I am wrong!)  Couldn't it be argued though (in laymans terms), that a lack of centripetal force could also be described as centrifugal force?  Scientifically correct or not, does that statement not essentially mean the same thing?  That would stand to reason as to why the term centrifugal force is so commonly used.

Anyway, this has strayed way off topic again!
e fail English? That's unpossible!

Believing is seeing the things which we don't believe we're seeing.... or something like that.

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cmdshft

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Dinosaurs and gravitational pull
« Reply #64 on: January 16, 2007, 09:09:09 PM »
The term is incorrect because the term "centrifuge" is used to name the machine which uses centripetal force to separate the different biological stuffs based on density. That's why it's called "The Imaginary Force", because it is derived from the centrifuge.

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BOGWarrior89

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Dinosaurs and gravitational pull
« Reply #65 on: January 16, 2007, 11:48:57 PM »
Quote from: "Big Giant Head"
I see what you're saying bogwarrior and I stand corrected (yes, I do admit if I am wrong!)  Couldn't it be argued though (in laymans terms), that a lack of centripetal force could also be described as centrifugal force?  Scientifically correct or not, does that statement not essentially mean the same thing?  That would stand to reason as to why the term centrifugal force is so commonly used.

Anyway, this has strayed way off topic again!


People also think that energy is equal to mass times the speed of light squared.  However, it is not; instead, E = (gamma) * m * c², where (gamma) = 1/[(1 - v²/c²)]^½ .

[edit]
The internet doesn't like to show gamma.

Also, Big Giant Head, it's not your fault you're wrong; someone didn't teach you it properly.

Dinosaurs and gravitational pull
« Reply #66 on: January 17, 2007, 01:12:30 AM »
Quote from: "BOGWarrior89"
Also, Big Giant Head, it's not your fault you're wrong; someone didn't teach you it properly.


I'm gonna get that 4th grade teacher when I go back to skool!
e fail English? That's unpossible!

Believing is seeing the things which we don't believe we're seeing.... or something like that.

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Erasmus

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Dinosaurs and gravitational pull
« Reply #67 on: January 17, 2007, 09:56:27 AM »
BOGWarrior, I thought you would have learned better by now.

Also,

Why did the chicken cross the Möbius strip?

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Erasmus

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Dinosaurs and gravitational pull
« Reply #68 on: January 17, 2007, 10:02:23 AM »
Quote from: "BOGWarrior89"
I admit to feeling a ficticious force, yes.


That's like saying you admit to sitting in an imaginary chair and typing on an imaginary keyboard, and somehow still manage post on (imaginary) forums.

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So, when you fly off the merry-go-round, you accelerate off of it?  No, you don't;


Yes, you do accelerate, at the rate ω² directly away from the axis of rotation.

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If the floor were frictionless, you'd fly off at a constant velocity.


A constant velocity in what reference frame?
Why did the chicken cross the Möbius strip?

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BOGWarrior89

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Dinosaurs and gravitational pull
« Reply #69 on: January 17, 2007, 10:54:02 AM »
Quote from: "Erasmus"
Quote from: "BOGWarrior89"
I admit to feeling a ficticious force, yes.


That's like saying you admit to sitting in an imaginary chair and typing on an imaginary keyboard, and somehow still manage post on (imaginary) forums.

No, it's not; I think I feel a pull to the outside, but it's only because of inertia.

Quote from: "Erasmus"
Quote
So, when you fly off the merry-go-round, you accelerate off of it?  No, you don't;


Yes, you do accelerate, at the rate ?² directly away from the axis of rotation.

Show me.

Quote from: "Erasmus"
Quote
If the floor were frictionless, you'd fly off at a constant velocity.


A constant velocity in what reference frame?

Yours.  The one that flew off with you.  Is there another of which I wasn't aware?

As a side note, I've already seen that xkcd comic.

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Erasmus

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Dinosaurs and gravitational pull
« Reply #70 on: January 18, 2007, 01:06:39 PM »
Quote from: "BOGWarrior89"
No, it's not; I think I feel a pull to the outside, but it's only because of inertia.


If you feel a pull, there's a pull.  Your measurements are just as valid as anybody else's (note: this does not apply to your opinions about mathematics).

Quote
Show me.


It is adequately reproduced in Wikipedia's article on fictitious forces.

Quote
Yours.  The one that flew off with you.  Is there another of which I wasn't aware?


Listen to what you're saying.  In your own reference frame (the one that flies off with you when you fly off a merry-go-round), you're always moving at a zero velocity.

The interesting thing is what happens before you fly off the merry-go-round, while you're still sitting on it (say, in a giant hamster ball, or  on a frictionless surface).  Everybody in the rotating reference frame of the merry-go-round (how could you not know that that reference frame exists), including you, observes a force on you causing you to "flee the centre".  If nothing balances this force, you accelerate outwards.
Why did the chicken cross the Möbius strip?

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BOGWarrior89

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Dinosaurs and gravitational pull
« Reply #71 on: January 19, 2007, 01:40:30 PM »
Quote from: "Erasmus"
Quote from: "BOGWarrior89"
No, it's not; I think I feel a pull to the outside, but it's only because of inertia.


If you feel a pull, there's a pull.  Your measurements are just as valid as anybody else's (note: this does not apply to your opinions about mathematics).

But I know I'm being pulled toward the inside, because if I wasn't, I'd fly off the merry-go-round, and NOT continue my circular motion.

I'm going to ignore that mathematics comment, Erasmus; I expected better from you.

Quote from: "Erasmus"
Quote
Show me.


It is adequately reproduced in Wikipedia's article on fictitious forces.

I meant with a picture/diagram.

Quote from: "Erasmus"
Quote
Yours.  The one that flew off with you.  Is there another of which I wasn't aware?


Listen to what you're saying.  In your own reference frame (the one that flies off with you when you fly off a merry-go-round), you're always moving at a zero velocity.

Sleep deprivation != good; I hope you'll allow me to retract that ugly statement.  I meant to say a non-rotating reference frame, i.e, someone watching you from a good, safe distance.

Quote from: "Erasmus"
The interesting thing is what happens before you fly off the merry-go-round, while you're still sitting on it (say, in a giant hamster ball, or  on a frictionless surface).  Everybody in the rotating reference frame of the merry-go-round (how could you not know that that reference frame exists), including you, observes a force on you causing you to "flee the centre".  If nothing balances this force, you accelerate outwards.

Really?  Because when I fly off, I fly off at a constant velocity (relative to a non-rotating reference frame), except there is some acceleration back towards the merry-go-round due to air resistance, which can be ignored.

Erasmus, I'm going assume that the centrifugal force "exists" in rotating-reference frames, because I haven't been taught anything about rotating reference frames yet.  But, if this is true, then I have one question, to which I think you may think you have already given me the answer:
If there is a centrifugal force, then why did my physics professor beat into our heads that there was no such thing?

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Erasmus

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Dinosaurs and gravitational pull
« Reply #72 on: January 21, 2007, 02:02:13 PM »
Quote from: "BOGWarrior89"
I meant with a picture/diagram.


What sort of picture/diagram?  What do you want it to illustrate?  If it's just "the centrifugal force" that you want to see, then draw a circle, draw a point somewhere inside the circle, and draw an arrow from that point in the outward radial direction.  Label that arrow "centrifugal force".

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I meant to say a non-rotating reference frame, i.e, someone watching you from a good, safe distance.


What's so special about such a reference frame?  I think you're prejudiced against rotating reference frames.  You're framist!  Stop being framist, BOGWarrior89.

Quote
Quote from: "Erasmus"
The interesting thing is what happens before you fly off the merry-go-round, while you're still sitting on it (say, in a giant hamster ball, or  on a frictionless surface). ...

Really?  Because when I fly off, ...


Emphasis already there.

Quote
But, if this is true, then I have one question, to which I think you may think you have already given me the answer:
If there is a centrifugal force, then why did my physics professor beat into our heads that there was no such thing?


Because your physics professor was stuck in (or was pretending to be stuck in) a pre-relativistic world where some reference frames are "special" and others are to be discounted as "not real".
Why did the chicken cross the Möbius strip?

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BOGWarrior89

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Dinosaurs and gravitational pull
« Reply #73 on: January 21, 2007, 04:09:51 PM »
Quote from: "Erasmus"
Quote from: "BOGWarrior89"
I meant with a picture/diagram.


What sort of picture/diagram?  What do you want it to illustrate?  If it's just "the centrifugal force" that you want to see, then draw a circle, draw a point somewhere inside the circle, and draw an arrow from that point in the outward radial direction.  Label that arrow "centrifugal force".

Funny.

Quote from: "Erasmus"
Quote from: "I"
But, if this is true, then I have one question, to which I think you may think you have already given me the answer:
If there is a centrifugal force, then why did my physics professor beat into our heads that there was no such thing?


Because your physics professor was stuck in (or was pretending to be stuck in) a pre-relativistic world where some reference frames are "special" and others are to be discounted as "not real".

Quote from: "Erasmus"
What's so special about such a reference frame?  I think you're prejudiced against rotating reference frames.  You're framist!  Stop being framist, BOGWarrior89.

I'm framist?

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Erasmus

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Dinosaurs and gravitational pull
« Reply #74 on: January 21, 2007, 04:11:51 PM »
Quote from: "BOGWarrior89"
I'm framist?


Yep.  You're just a dirty framist.  Your professor was either a framist too, or was harkening back to a pre-coordinate-egalitarian age.
Why did the chicken cross the Möbius strip?

Dinosaurs and gravitational pull
« Reply #75 on: January 22, 2007, 12:27:55 AM »
Quote from: "Masterchief2219"
Quote from: "weevil"
Hmmmm very interesting....why can't they? Maybe if they examined fossils of the size of animals living back then and the size of animals now!!!!

Do you honestly think that gravity is the only possible factor that would effect the size of animals?


It is a determining factor in a lot of aspects for animals.

For example, why aren't Elephants as agile as cats? The required bone mass to support so much body and muscle would mean the entire elephant (or near enough) would have to be made of bone. The more bone required, the heavier the animal gets, the greater the need for muscle to move the bone. More muscle means more size means more bone means it's just a hell of a lot easier to make elephants somewhat clumsy rather then agile.

This is also why Ants or other "exoskeleton" animals can't grow much larger then they are now. The amount of energy it would take to move such animals would just be ridicules.

BUT there are other things that determine possible animal size, environment for one. Forested areas are likely to produce smaller animals while open plains and savannahs will produce larger animals.

Oh and looking at fossils would do absolutely nothing to determine gravitational force. Seeing as they are fossils and thus ROCK rather then bone. You couldn't even accurately determine the weight of the original bones before they became fossilized.
Quote from: BOGWarrior89

I'm giving you five points for that one


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Masterchef

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Dinosaurs and gravitational pull
« Reply #76 on: January 22, 2007, 06:34:55 AM »
Quote from: "Wolfwood"
For example, why aren't Elephants as agile as cats? The required bone mass to support so much body and muscle would mean the entire elephant (or near enough) would have to be made of bone. The more bone required, the heavier the animal gets, the greater the need for muscle to move the bone. More muscle means more size means more bone means it's just a hell of a lot easier to make elephants somewhat clumsy rather then agile.

Elephants aren't as agile as cats simply because they have a lot of mass, and therefore a lot of inertia.Sure, thats got something to do with gravity, but there still is nothing to suggest that gravity kept them from getting bigger.

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This is also why Ants or other "exoskeleton" animals can't grow much larger then they are now. The amount of energy it would take to move such animals would just be ridicules.

Thanks for the speculation, but I am afraid that isn't worth much in a debate. The truth is that prehistoric insects were 100 times the size of the ones we have now.

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BUT there are other things that determine possible animal size, environment for one. Forested areas are likely to produce smaller animals while open plains and savannahs will produce larger animals.

Yes, which is exactly what I said. When there are literally thousands of possible causes to factor in, it is ignorant to say that ________ was definitely caused by gravity.

Dinosaurs and gravitational pull
« Reply #77 on: January 22, 2007, 06:49:31 PM »
Quote from: "Masterchief2219"
Quote from: "Wolfwood"
For example, why aren't Elephants as agile as cats? The required bone mass to support so much body and muscle would mean the entire elephant (or near enough) would have to be made of bone. The more bone required, the heavier the animal gets, the greater the need for muscle to move the bone. More muscle means more size means more bone means it's just a hell of a lot easier to make elephants somewhat clumsy rather then agile.

Elephants aren't as agile as cats simply because they have a lot of mass, and therefore a lot of inertia.Sure, that's got something to do with gravity, but there still is nothing to suggest that gravity kept them from getting bigger.

Quote
This is also why Ants or other "exoskeleton" animals can't grow much larger then they are now. The amount of energy it would take to move such animals would just be ridicules.

Thanks for the speculation, but I am afraid that isn't worth much in a debate. The truth is that prehistoric insects were 100 times the size of the ones we have now.

Quote
BUT there are other things that determine possible animal size, environment for one. Forested areas are likely to produce smaller animals while open plains and savannahs will produce larger animals.

Yes, which is exactly what I said. When there are literally thousands of possible causes to factor in, it is ignorant to say that ________ was definitely caused by gravity.


1) Elephants aren't agile because gravity makes them heavy and their bone structure isn't stable enough to handle running around like hyper active dogs like in George of the Jungle. Gravity doesn't stop them from growing larger, but what reason would there be to grow larger? They are already too large to fall prey to any predator in Africa as it is. In truth large size becomes an inconvenience and is only worth something as a deterrent for predators.

2) Link to some form of evidence to this effect? I never heard of insects being more then a foot in prehistoric times.

3) Gravity does put a natural LIMIT on size. But that limit is subject to change based on body structure and materials used. If nature produced a bone that was stronger and lighter, as well as muscles that were stronger and lighter, then animals as big as sky scrappers could conceivably exist. But other things have to be factored in, such as blood circulation and respiratory systems. Amount of food needed to support such massive creatures and countless other factors that limit animal sizes.

Another reason why Dinos got to be so huge compared to our era is that some animals (dinos likely among them) have no natural limit on size that they grow to. Humans and mammals grow to a specific predetermined size and that's it, they stop no matter what. Some animals don't have that limit and will continue devoting energy from food to growth and will only stop growing during mating seasons (when energy is needed for other activities). Obviously since Elephants are mammals, they had to evolve to that size. Dinos merely had to survive long enough to grow to that size, so gaining mass was easier especially for herd animals who had a better chance to survive then loners. Also as herbivores grew in mass, carnivores had to grow in mass as well, just so they had a chance at catching and consuming food.
Quote from: BOGWarrior89

I'm giving you five points for that one


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dbighead77

Re: Dinosaurs and gravitational pull
« Reply #78 on: July 17, 2007, 06:58:14 PM »
I don't want to ruin your conversation, but what is so hard to understand about centrifugal forces being imaginary. There is no such thing. Every time you feel a "pull" to the outside of a curve, it's your mass going through Newton's first law: Inertia. When going through circular motion, your body is being pulled to the inside with a centripetal force. However, your body has inertia, and wants to continue in a STRAIGHT line, which is tangent to the path which it is being forced to follow.

One thing that bugs me about Flat Earthers is this: Do they or don't they believe in Newton's laws? Or are there two sects that disagree on Newton?

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cmdshft

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Re: Dinosaurs and gravitational pull
« Reply #79 on: July 17, 2007, 07:59:14 PM »
I don't want to ruin your conversation, but what is so hard to understand about centrifugal forces being imaginary. There is no such thing. Every time you feel a "pull" to the outside of a curve, it's your mass going through Newton's first law: Inertia. When going through circular motion, your body is being pulled to the inside with a centripetal force. However, your body has inertia, and wants to continue in a STRAIGHT line, which is tangent to the path which it is being forced to follow.

One thing that bugs me about Flat Earthers is this: Do they or don't they believe in Newton's laws? Or are there two sects that disagree on Newton?

You're ruining a conversation that's been dead for nearly 6 months. Way to fail.  ;)

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dbighead77

Re: Dinosaurs and gravitational pull
« Reply #80 on: July 17, 2007, 08:47:41 PM »
I'm just wondering where Newton comes into this whole thing.

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cmdshft

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Re: Dinosaurs and gravitational pull
« Reply #81 on: July 17, 2007, 09:18:29 PM »
I'm just wondering where Newton comes into this whole thing.

He doesn't, he's dead, and thus, please just let this die too.

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Raist

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Re: Dinosaurs and gravitational pull
« Reply #82 on: July 17, 2007, 09:23:47 PM »
So could the gravitational pull have been affected if the impact altered the axis of the earth? Re: the moon being a chunk of earth....I thought that when they brought back moon rocks it was ascertained that the moon was older than the earth.  It seems strange that such large creatures were the first to roam the earth.

Because rocks on the earth are constantly being recycled by volcanic/plate techtonics. The moon having no volcanic activity has rocks that formed the day it formed. The earth on the other hand does not.