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| Author |
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| ashok |
 Posted: Sat Sep 11, 2004 7:02 am |
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Guest
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If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
consider the following illustration.
if i hold the tube in hand and start whirling the rope,the rope starts
pulling itself outwards.?
will someone please tell me what forces are involed?
O----------------| |
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O
regds,
ypj |
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| Martin Hogbin |
| Posted: Sat Sep 11, 2004 7:02 am |
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"ashok" <arjdombivli@indiatimes.com> wrote in message news:1dc813f.0409110502.752b0dd7@posting.google.com...
[quote:d613151e48]If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
consider the following illustration.
if i hold the tube in hand and start whirling the rope,the rope starts
pulling itself outwards.?
will someone please tell me what forces are involed?
O----------------| |
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O
[/quote:d613151e48]
Answer me this question first.. You throw a stone
which has a rope attached as the stone moves it pulls
rope from your hand. What force is involved? |
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| Sam Wormley |
| Posted: Sat Sep 11, 2004 8:16 am |
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ashok wrote:
[quote:529953c0d3]If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
consider the following illustration.
if i hold the tube in hand and start whirling the rope,the rope starts
pulling itself outwards.?
will someone please tell me what forces are involed?
O----------------| |
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O
regds,
ypj
[/quote:529953c0d3]
See: http://scienceworld.wolfram.com/physics/CentrifugalForce.html |
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| Richard Henry |
| Posted: Sat Sep 11, 2004 11:09 am |
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"ashok" <arjdombivli@indiatimes.com> wrote in message
news:1dc813f.0409110502.752b0dd7@posting.google.com...
[quote:c506bee8e1]If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
consider the following illustration.
if i hold the tube in hand and start whirling the rope,the rope starts
pulling itself outwards.?
will someone please tell me what forces are involed?
O----------------| |
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O
[/quote:c506bee8e1]
Not centrifugal. Certainly not centrifugal. Don't even go there. |
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| Morituri-Max |
| Posted: Sat Sep 11, 2004 11:37 am |
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Richard Henry wrote:
[quote:9c101961d6]Not centrifugal. Certainly not centrifugal. Don't even go there.
[/quote:9c101961d6]
If you know what it isn't, tell us what it IS. |
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| mitch perkins |
| Posted: Sat Sep 11, 2004 11:54 pm |
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"Morituri-Max" <newage@sendarico.net> wrote in message news:<3JG0d.13295$le.7138@fe2.texas.rr.com>...
[quote:7a87198984]Richard Henry wrote:
Not centrifugal. Certainly not centrifugal. Don't even go there.
If you know what it isn't, tell us what it IS.
[/quote:7a87198984]
Centrifugal in the non-inertial (rotating?) frame?
In the inertial frame of someone watching the whirling, what *is*
the force exerted by the whirler's arm?
In reading about F=ma, the words "a force" have me confused (not
hard to do).
Does [a force] = [a fundamental force] ?
If so, the whirling must be electro-magnetic.
I feel stupid.
But this is neat, and so far I've answered every question correctly:
<http://www.physicsclassroom.com/Class/1DKin/U1L1d.html>
Troll Shoulder was an almost *immediate* failure! 
It's like littering: the first piece of garbage gives licence to the
heap that follows. Well...I've no shortage of garbage. Heave-ho!
Mitch |
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| The Ghost In The Machine |
| Posted: Sun Sep 12, 2004 5:58 pm |
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In sci.physics, ashok
<arjdombivli@indiatimes.com>
wrote
on 11 Sep 2004 06:02:07 -0700
<1dc813f.0409110502.752b0dd7@posting.google.com>:
[quote:bc5fc571c6]If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
[/quote:bc5fc571c6]
You.
You are holding the rope, swinging the mass at the end thereof
around your head. Were you to let the rope go it would traverse
a straight line (well, as straight as the Earth's gravfield would
allow, anyway). Since it's traveling a circular path, it is
being accelerated -- your hand is applying centri*petal* force
to the rope.
By Newton's Third, the rope is also applying a force on your hand,
tugging at it. At least, I think that's correctly expressed.
"Centrifugal force" is an illusion, albeit a very persistent one.
A common carnival ride, for instance, is basically a large,
rotating wheel (some variants tilt the wheel up into the air
during the ride, some do not). When inside such a ride, one
experiences a force, but one is also not in an inertial
reference frame, as one is being accelerated -- usually by the
ridge of the wheel, pushing on one's back.
Same principle.
[quote:bc5fc571c6]
consider the following illustration.
if i hold the tube in hand and start whirling the rope,the rope starts
pulling itself outwards.?
will someone please tell me what forces are involed?
O----------------| |
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O
regds,
ypj
[/quote:bc5fc571c6]
--
#191, ewill3@earthlink.net
It's still legal to go .sigless. |
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| mitch perkins |
| Posted: Mon Sep 13, 2004 10:44 am |
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The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote in message news:<o0ve12-s01.ln1@lexi2.athghost7038suus.net>...
[quote:04e565c75a]In sci.physics, ashok
arjdombivli@indiatimes.com
wrote
on 11 Sep 2004 06:02:07 -0700
1dc813f.0409110502.752b0dd7@posting.google.com>:
If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
You.
[/quote:04e565c75a]
<http://encyclopedia.thefreedictionary.com/Force%20(physics)>
<http://encyclopedia.thefreedictionary.com/Fundamental%20force>
Still foggy wrt the origin of the force [you] is exerting. It's a
problem of definition I'm having.
[quote:04e565c75a]You are holding the rope, swinging the mass at the end thereof
around your head. Were you to let the rope go it would traverse
a straight line (well, as straight as the Earth's gravfield would
allow, anyway). Since it's traveling a circular path, it is
being accelerated -- your hand is applying centri*petal* force
to the rope.
[/quote:04e565c75a]
What is responsible for my hand's ability to apply this force? Via
chemical processes I convert energy into work (?) Is a fundamental
force involved in making the chemical process possible?
Apologies; this is a mental block I have been unable to smash with
the mighty Googlehammer.
[quote:04e565c75a]
By Newton's Third, the rope is also applying a force on your hand,
tugging at it. At least, I think that's correctly expressed.
[/quote:04e565c75a]
Looks like it. ~ )
<http://encyclopedia.thefreedictionary.com/third%20law>
"Whenever one body exerts force upon a second body, the second body
exerts an equal and opposite force upon the first body.
For every action, there is an equal and opposite reaction."
[quote:04e565c75a]"Centrifugal force" is an illusion, albeit a very persistent one.
A common carnival ride, for instance, is basically a large,
rotating wheel (some variants tilt the wheel up into the air
during the ride, some do not). When inside such a ride, one
experiences a force, but one is also not in an inertial
reference frame, as one is being accelerated -- usually by the
ridge of the wheel, pushing on one's back.
[/quote:04e565c75a]
This is awesome: (for OP)
<http://math.ucr.edu/home/baez/physics/General/Centrifugal/centri.html>
Mitch |
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| The Ghost In The Machine |
| Posted: Tue Sep 14, 2004 10:07 pm |
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In sci.physics, mitch perkins
<mitchsperkins@yahoo.com>
wrote
on 13 Sep 2004 09:44:32 -0700
<64dddc3d.0409130844.3fd7e996@posting.google.com>:
[quote:13cbbf5e8f]The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote in message news:<o0ve12-s01.ln1@lexi2.athghost7038suus.net>...
In sci.physics, ashok
arjdombivli@indiatimes.com
wrote
on 11 Sep 2004 06:02:07 -0700
1dc813f.0409110502.752b0dd7@posting.google.com>:
If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
You.
http://encyclopedia.thefreedictionary.com/Force%20(physics)
http://encyclopedia.thefreedictionary.com/Fundamental%20force
Still foggy wrt the origin of the force [you] is exerting. It's a
problem of definition I'm having.
[/quote:13cbbf5e8f]
To wander into that domain will require biochemistry. 
Suffice it to say that you're holding the rope, which
requires muscle contraction, energy expenditure (sugar
burn or ATP=>ADP conversion), etc.
[quote:13cbbf5e8f]
You are holding the rope, swinging the mass at the end thereof
around your head. Were you to let the rope go it would traverse
a straight line (well, as straight as the Earth's gravfield would
allow, anyway). Since it's traveling a circular path, it is
being accelerated -- your hand is applying centri*petal* force
to the rope.
What is responsible for my hand's ability to apply this force? Via
chemical processes I convert energy into work (?)
[/quote:13cbbf5e8f]
More or less.
[quote:13cbbf5e8f]Is a fundamental
force involved in making the chemical process possible?
[/quote:13cbbf5e8f]
Yes, the electroweak force, if I'm not mistaken. Or one can
look at bond enthalpies -- roughly speaking, the energy released
when atoms are put together in interesting ways.
But that's getting rather far afield of physics.
[quote:13cbbf5e8f]Apologies; this is a mental block I have been unable to smash with
the mighty Googlehammer.
By Newton's Third, the rope is also applying a force on your hand,
tugging at it. At least, I think that's correctly expressed.
Looks like it. ~)
http://encyclopedia.thefreedictionary.com/third%20law
"Whenever one body exerts force upon a second body, the second body
exerts an equal and opposite force upon the first body.
For every action, there is an equal and opposite reaction."
"Centrifugal force" is an illusion, albeit a very persistent one.
A common carnival ride, for instance, is basically a large,
rotating wheel (some variants tilt the wheel up into the air
during the ride, some do not). When inside such a ride, one
experiences a force, but one is also not in an inertial
reference frame, as one is being accelerated -- usually by the
ridge of the wheel, pushing on one's back.
This is awesome: (for OP)
http://math.ucr.edu/home/baez/physics/General/Centrifugal/centri.html
[/quote:13cbbf5e8f]
Yep, looks about right. :-)
[quote:13cbbf5e8f]
Mitch
[/quote:13cbbf5e8f]
--
#191, ewill3@earthlink.net
It's still legal to go .sigless. |
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| Randy Poe |
| Posted: Wed Sep 15, 2004 4:20 am |
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Guest
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mitchsperkins@yahoo.com (mitch perkins) wrote in message news:<64dddc3d.0409130844.3fd7e996@posting.google.com>...
[quote:2daecb1224]What is responsible for my hand's ability to apply this force? Via
chemical processes I convert energy into work (?) Is a fundamental
force involved in making the chemical process possible?
[/quote:2daecb1224]
The mechanical force comes from motion of muscle fibers
against each other. There seem to be two different questions
here: what process produces the energy (chemical reactions
fueled by ATP) and what process converts biological energy
into muscle contractions?
[quote:2daecb1224]Apologies; this is a mental block I have been unable to smash with
the mighty Googlehammer.
[/quote:2daecb1224]
You ought to be able to find plenty on how muscles work.
The energy source is chemical, meaning binding energy is
being released. I suppose you could then ask what force is
involved there. Ultimately binding energy is a consequence
of the quantum mechanics of the Coulomb force.
- Randy |
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| Mike |
| Posted: Wed Sep 15, 2004 11:28 am |
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arjdombivli@indiatimes.com (ashok) wrote in message news:<1dc813f.0409110502.752b0dd7@posting.google.com>...
[quote:8aeb4e34d3]If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
consider the following illustration.
if i hold the tube in hand and start whirling the rope,the rope starts
pulling itself outwards.?
will someone please tell me what forces are involed?
O----------------| |
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O
regds,
ypj
[/quote:8aeb4e34d3]
If the rope bottom end is released after the rock is on a circular
orbit, there is no reaction on the tube-hand system (assume no
friction on the tube rim) and the stone will move on a straight line
with constant velocity equal the orbital velocity at the time of
release. There are no forces involved, that is just inertial motion.
If the rope is held fixed then there is a centripetal force on the
stone and its reaction is a centrifugal force on the hand.
Now, some cranks here think centrifugal forces are ficticious because
they heard that someplace. Centrifugal forces are very real and all
you need to realize that is riding a bicycle around a curb at high
speed. What is ficticious is the force needed in a non-inertial frame
to explain motion and apply Newton 2nd law. That force may happen to
be centrifugal but that does not mean centrifugal forces are
ficticious. They are ficticious when applying 2nd law in a
non-inertial reference frame.
Mike |
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| mitch perkins |
| Posted: Wed Sep 15, 2004 12:01 pm |
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Guest
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The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote in message news:<a4dj12-004.ln1@lexi2.athghost7038suus.net>...
[quote:1bf540ad3a]In sci.physics, mitch perkins
mitchsperkins@yahoo.com
wrote
on 13 Sep 2004 09:44:32 -0700
64dddc3d.0409130844.3fd7e996@posting.google.com>:
The Ghost In The Machine <ewill@aurigae.athghost7038suus.net> wrote in message news:<o0ve12-s01.ln1@lexi2.athghost7038suus.net>...
In sci.physics, ashok
arjdombivli@indiatimes.com
wrote
on 11 Sep 2004 06:02:07 -0700
1dc813f.0409110502.752b0dd7@posting.google.com>:
If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
You.
http://encyclopedia.thefreedictionary.com/Force%20(physics)
http://encyclopedia.thefreedictionary.com/Fundamental%20force
Still foggy wrt the origin of the force [you] is exerting. It's a
problem of definition I'm having.
To wander into that domain will require biochemistry.
[/quote:1bf540ad3a]
There is a saying, can't remember it right now, something about
physics being the only science; the others are stamp collecting.
Reminds me of this: Stock car racing is the only sport; the rest are
all games.
Seriously though, doesn't chemistry still describe tiny bits of
stuff engaging in what amount to physical interactions? Clearly the
word is a useful distinction, but from it's (my percieved) "subset"
status arose my question. Which you relieved me much by answering; I
had thought the question perhaps too stupid to warrant a reply. So
thanks!
[quote:1bf540ad3a]Suffice it to say that you're holding the rope, which
requires muscle contraction, energy expenditure (sugar
burn or ATP=>ADP conversion), etc.
[/quote:1bf540ad3a]
<snip>
[quote:1bf540ad3a]Is a fundamental
force involved in making the chemical process possible?
Yes, the electroweak force, if I'm not mistaken.
[/quote:1bf540ad3a]
Reeeally! This gives me something to work with.
[quote:1bf540ad3a]Or one can
look at bond enthalpies -- roughly speaking, the energy released
when atoms are put together in interesting ways.
[/quote:1bf540ad3a]
<http://www.webchem.net/notes/how_far/enthalpy/bondenthalpy.htm>
"Their main use is in working out enthalpy changes for reactions. If
we know the amount of energy needed to break a bond (endothermic), and
the amount of energy we get back when a new bond forms (exothermic),
then we can quite easily work out an approximate (because of the
average nature of the bond enthalpies) value for the enthalpy change!"
Something to look into further - thanks again.
Mitch |
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| mitch perkins |
| Posted: Wed Sep 15, 2004 12:22 pm |
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poespam-trap@yahoo.com (Randy Poe) wrote in message news:<df76407e.0409150220.60d39574@posting.google.com>...
[quote:7629777faa]mitchsperkins@yahoo.com (mitch perkins) wrote in message news:<64dddc3d.0409130844.3fd7e996@posting.google.com>...
What is responsible for my hand's ability to apply this force? Via
chemical processes I convert energy into work (?) Is a fundamental
force involved in making the chemical process possible?
The mechanical force comes from motion of muscle fibers
against each other. There seem to be two different questions
here: what process produces the energy (chemical reactions
fueled by ATP) and what process converts biological energy
into muscle contractions?
Apologies; this is a mental block I have been unable to smash with
the mighty Googlehammer.
You ought to be able to find plenty on how muscles work.
[/quote:7629777faa]
Yes. I only looked at "force" and "fundamental force".
[quote:7629777faa]
The energy source is chemical, meaning binding energy is
being released. I suppose you could then ask what force is
involved there. Ultimately binding energy is a consequence
of the quantum mechanics of the Coulomb force.
[/quote:7629777faa]
<http://scienceworld.wolfram.com/physics/CoulombForce.html>
Thanks!
Question is, since there are but three (G is "fictitious"?)
*fundamental* forces, does this mean that *any* observable phenomenon
will have at it's root one of these three?
It's pretty clear why a fundamental force is not referred to in
every instance of investigation; it is not always directly relevant.
Mitch |
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| Randy Poe |
| Posted: Wed Sep 15, 2004 5:53 pm |
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Guest
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mitchsperkins@yahoo.com (mitch perkins) wrote in message news:<64dddc3d.0409151022.45cee43a@posting.google.com>...
[quote:75f6aad6a0]poespam-trap@yahoo.com (Randy Poe) wrote in message news:<df76407e.0409150220.60d39574@posting.google.com>...
mitchsperkins@yahoo.com (mitch perkins) wrote in message news:<64dddc3d.0409130844.3fd7e996@posting.google.com>...
What is responsible for my hand's ability to apply this force? Via
chemical processes I convert energy into work (?) Is a fundamental
force involved in making the chemical process possible?
The mechanical force comes from motion of muscle fibers
against each other. There seem to be two different questions
here: what process produces the energy (chemical reactions
fueled by ATP) and what process converts biological energy
into muscle contractions?
Apologies; this is a mental block I have been unable to smash with
the mighty Googlehammer.
You ought to be able to find plenty on how muscles work.
Yes. I only looked at "force" and "fundamental force".
The energy source is chemical, meaning binding energy is
being released. I suppose you could then ask what force is
involved there. Ultimately binding energy is a consequence
of the quantum mechanics of the Coulomb force.
http://scienceworld.wolfram.com/physics/CoulombForce.html
[/quote:75f6aad6a0]
Actually it's more direct than I said. Friction and the
fact that solids push against each other, i.e., act
"solid", are also consequences of Coulomb interactions.
My guess is that muscle motion, which involves fibers
sliding across each other, also involves Coulomb
forces.
[quote:75f6aad6a0]Thanks!
Question is, since there are but three (G is "fictitious"?)
[/quote:75f6aad6a0]
It is?
[quote:75f6aad6a0]*fundamental* forces, does this mean that *any* observable phenomenon
will have at it's root one of these three?
[/quote:75f6aad6a0]
Yes.
[quote:75f6aad6a0]It's pretty clear why a fundamental force is not referred to in
every instance of investigation; it is not always directly relevant.
[/quote:75f6aad6a0]
Yes. Since Coulomb forces dominate practically every aspect
of our life, it's not that interesting to ask which force is
at work in an average life situation. It's like going around
an "everything for $1" store asking the prices of things.
More interesting probably to speculate on where the energy
comes from and how it is converted from one form to another.
I think any mechanical motion that is biological in origin
is fascinating. Did you ever hear about those protozoans with
the little propellors?
- Randy |
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| The Ghost In The Machine |
| Posted: Thu Sep 16, 2004 10:13 am |
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In sci.physics, Mike
<eleatis@yahoo.gr>
wrote
on 15 Sep 2004 10:28:59 -0700
<9c1b39be.0409150928.37a0aaea@posting.google.com>:
[quote:078300eb63]arjdombivli@indiatimes.com (ashok) wrote in message news:<1dc813f.0409110502.752b0dd7@posting.google.com>...
If I start whirling a rope whose outer end is tied to a stone, the
radius of the whirling goes on increasing.(the rope get pulled from my
hand).
which is this force which forces rope to get pulled.?
consider the following illustration.
if i hold the tube in hand and start whirling the rope,the rope starts
pulling itself outwards.?
will someone please tell me what forces are involed?
O----------------| |
| |
| |
| |
| |
|
|
O
regds,
ypj
If the rope bottom end is released after the rock is on a circular
orbit, there is no reaction on the tube-hand system (assume no
friction on the tube rim) and the stone will move on a straight line
with constant velocity equal the orbital velocity at the time of
release. There are no forces involved, that is just inertial motion.
If the rope is held fixed then there is a centripetal force on the
stone and its reaction is a centrifugal force on the hand.
Now, some cranks here think centrifugal forces are ficticious because
they heard that someplace. Centrifugal forces are very real and all
you need to realize that is riding a bicycle around a curb at high
speed. What is ficticious is the force needed in a non-inertial frame
to explain motion and apply Newton 2nd law. That force may happen to
be centrifugal but that does not mean centrifugal forces are
ficticious. They are ficticious when applying 2nd law in a
non-inertial reference frame.
Mike
[/quote:078300eb63]
Centrifugal forces are illusion and are an artifact of inertia
and centri*petal* forces.
If the OP were to not apply any force on the tube, the tube
would follow the rope and the rope would follow the stone,
in a straight line. There are admittedly some issues here --
one variant of this device would be a common tetherball, but
one might also notice the bending of the support as the tetherball
spins around it.
I've already mentioned the carnival ride; the wall pushes inward
in that case.
--
#191, ewill3@earthlink.net
It's still legal to go .sigless. |
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