On 21/02/2022 15:44, Robin wrote:
>
> On 21/02/2022 14:18, Java Jive wrote:
>>
>> On 21/02/2022 14:01, David Woolley wrote:
>>>
>>> Except that Coriolis forces  mean the wind doesn't actually flow in
>>> the right direction to fill the low pressure!
>>
>> <pedant>I'm not sure 'force' is the right word there!</pedant>
>
> When I dabbled in physics many years ago "Coriolis force" was by
> definition a fictional force so - unless the meaning has changed - it
> seems an acceptable term in that context.

Well, I've never heard it called that, so my first reaction was to ask
myself: "I wonder if he's confusing it with the centrifugal force,
which, although it's just an inertial effect, is often called a
fictional force, because it has the same units as a real force?"

However, Wikipedia agrees with you, and even gives a formula for the
Coriolis effect, though unfortunately they don't show it's derivation.
For Applied Maths A-level, we did many, many examples of satellite
orbits, etc, so I'm very familiar with the term in the formula for the
centrifugal effect, which is m.v^2/r or m.r.omega^2, where omega=v/r,
but I've never seen the Coriolis effect treated as a fictional force before.

FTR, the formula they give for the Coriolis 'force' is ...
-2.m.v.omega or -2.m.v^2/r or -2.m.r.omega^2
.... but vectors are involved - it's a cross-product - which is
difficult to convey here in simple ASCII text, but those interested can
take a look here:

https://en.wikipedia.org/wiki/Coriolis_force

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 21/02/2022 16:04, NY wrote:
>
> "Java Jive" <java@evij.com.invalid> wrote in message
> news:sv0cfu$2l5$1@dont-email.me...
>>
>> (or more strictly still '*a* Coriolis effect' because there are
>> others, such as dropping a rock from a high enough tower causes it to
>> land slightly ahead of directly under the point where it was dropped,
>> because initially it was travelling slightly faster through space and
>> therefore overtakes that point).
>
> Surely the lateral speed of the rock (relative to a stationary observer
> out in space) remains the same as the earth's speed, no matter how much
> the rock accelerates in a downward direction due to gravity and is
> decelerated by speed-dependent slowing due to air resistance. Or to put
> it another way, the rock remains stationary relative to the ground in a
> lateral direction. That's assuming there's no wind - ie that the
> atmosphere is rotating at the same speed as the earth and the tower.

Theoretically, ignoring air-resistance, comparing the linear speeds of
the rock and the point on earth's surface directly underneath where it
is dropped from, the rock has a larger radius of spin around the earth's
axis by an amount equal to the height of the tower, therefore when it is
dropped its linear velocity in the direction of earth's spin is slightly
faster than the point on earth's surface directly underneath, so it will
land slightly ahead of it.

> Or am I about to learn something? Is the effect that you are describing
> one that only exists because of the earth's atmosphere, or would it also
> be true in a vacuum?

It would certainly be true in a vacuum, and also in air, but the
latter's resistance would reduce the effect, perhaps enough to make it
immeasurable.

But see also my other post where I admit that I've always called the
Coriolis effect is actually classed as a fictitious force, I'd just
never heard it called that before.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

In article <sv0eb9$h67$1@dont-email.me>,
Woody <harrogate3@ntlworld.com> wrote:

> Clearly there are a lot of people on this group that <do> understand
> weather and isobaric charts and thus probably the Shipping Forecast?

> Slightly off line then could I recommend to those with such
> understanding a book called 'Attention All Shipping' by Charlie
> Connelly. He visits every SF area or at least as near as he can get to
> them. Fascinating reading but just slightly tongue in cheek.

Heard a talk on Zoom - with pictures, by him during lockdown about this.

--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle

On 21/02/2022 16:51, Java Jive wrote:

>
> But see also my other post where I admit that I've always called the
> Coriolis effect is actually classed as a fictitious force, I'd just
> never heard it called that before.
>

You may well have been using "the Coriolis effect" accurately. The 2
terms can co-exist amicably with the [fictitious] force explaining the
effect. And I /think/ making it easier to do sums in some practical
scenarios. (I certainly hope so as I couldn't now do sums with the
cross-vectors if me life depended on it. And the more advanced
equations of motion for a particle in a rotating frame but a distant
nightmare.)

--
Robin
reply-to address is (intended to be) valid

Jim Lesurf wrote:

> Andy Burns wrote:
>
>> the BBC weather app forecasts in 1 hour slots for 14
>> days ahead, which strikes me as an utterly pointless level of detail.
>
> I find that very handy.

9am tomorrow morning: good

9am in a couple of days time: not bad

but 9am on the sunday after next: fantasy weather.

On 21/02/2022 15:31, Pamela wrote:
> On 10:37 21 Feb 2022, Jeff Layman said:
>
>> On 21/02/2022 08:57, Mike Cooper wrote:
>>> This is good
>>>
>>> https://www.met.ie/forecasts/atlantic-charts/precipitation-pressure
>>>
>>>
>>> On Wednesday, 7 February 2018 at 10:32:21 UTC, Ian Jackson wrote:
>>>> The BBC have introduced a new, improved style of presenting the
>>>> weather.
>>>>
>>>> On their website, there no longer appears to be a proper 'Jack
>>>> Scott' weather map (Surface Pressure Chart), as per
>>>> <https://www.metoffice.gov.uk/public/weather/surface-pressure/#?tab=
>>>> surfa cePressureColour&fcTime=1517918400>
>>>>
>>>> Is it there somewhere, and I can't find it - or do the BBC feel
>>>> that nobody was interested?
>>
>> If you're interested in just about every aspect of what the weather
>> is doing anywhere in the world, then the best website I've found is
>> https://earth.nullschool.net/. This url centres on the UK:
>> <https://earth.nullschool.net/#2022/02/21/2000Z/wind/isobaric/1000hPa/
>> orthographic=-6.04,53.98,3226>
>>
>> If you click on "earth" at bottom left, you can change the parameters
>> of what you're looking at. It's worth a play, but you may find
>> yourself spending rather a lot of time on the site!
>
> Lovely graphics. No forecast?

Just below the coloured scale is something called "Control". Using >
goes forward an hour; using >> goes forward 8 hours. If you click on the
icon next to "Now" you can choose a date up to 4 days ahead. It's a
forecast of sorts, I suppose.

--

Jeff

"Java Jive" <java@evij.com.invalid> wrote in message
news:sv0fuf$tgt$1@dont-email.me...
> On 21/02/2022 16:04, NY wrote:
>>
>> "Java Jive" <java@evij.com.invalid> wrote in message
>> news:sv0cfu$2l5$1@dont-email.me...
>>>
>>> (or more strictly still '*a* Coriolis effect' because there are others,
>>> such as dropping a rock from a high enough tower causes it to land
>>> slightly ahead of directly under the point where it was dropped, because
>>> initially it was travelling slightly faster through space and therefore
>>> overtakes that point).
>>
>> Surely the lateral speed of the rock (relative to a stationary observer
>> out in space) remains the same as the earth's speed, no matter how much
>> the rock accelerates in a downward direction due to gravity and is
>> decelerated by speed-dependent slowing due to air resistance. Or to put
>> it another way, the rock remains stationary relative to the ground in a
>> lateral direction. That's assuming there's no wind - ie that the
>> atmosphere is rotating at the same speed as the earth and the tower.
>
> Theoretically, ignoring air-resistance, comparing the linear speeds of the
> rock and the point on earth's surface directly underneath where it is
> dropped from, the rock has a larger radius of spin around the earth's axis
> by an amount equal to the height of the tower, therefore when it is
> dropped its linear velocity in the direction of earth's spin is slightly
> faster than the point on earth's surface directly underneath, so it will
> land slightly ahead of it.

Yeeeeeeeeees (he says, reluctantly!) you have a very good point there. But
wouldn't the motion of the falling rock be along a radius of the earth so
the rock would remain parallel to the building? Or is the slight error of
the two sides of the building being parallel rather than converging radii
enough to give a noticeable error in the landing position. As a matter of
interest, how large is the effect, in terms of horizontal displacement as a
function of building height?

I think I believe you, but in true "take nobody's word for it" scientific
tradition I'm going to have to test it to prove it to myself. Now where's
there a nice tall tower block that I can drop a stone off without any danger
of it hitting someone below?

"Java Jive" <java@evij.com.invalid> wrote in message
news:sv0evm$m5c$1@dont-email.me...
> Well, I've never heard it called that, so my first reaction was to ask
> myself: "I wonder if he's confusing it with the centrifugal force, which,
> although it's just an inertial effect, is often called a fictional force,
> because it has the same units as a real force?"

I was always confused when centrifugal force was described as fictional
because it can definitely be felt and demonstrated. If you tie a weight to a
piece of string and whirl it round your head, you can feel a force acting
outwards on your hand. If you attach a light weight to one end of the
string, thread it through a cotton reel as a "bearing" and attach a heavier
weight to the other end, the whirling light weight can cause the heavier
weight to rise, as if there was a force acting outwards on the whirling
weight and upwards (via the "bearing") on the heavy weight. I suppose it's
all to do with frame of reference: we tend to judge it wrt to the centre of
rotation as the frame of reference, rather than the FoR of a stationary
bystander.

Maybe it can all be waved away by saying the centrifugal force is a
fictional equal-and-opposite reaction to the very real and undisputed
centripetal force, such that the rotating object remains at a constant
radius rather than actually spiralling towards the centre as CP force on its
own would imply.

In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
> I was always confused when centrifugal force was described as fictional
> because it can definitely be felt and demonstrated. If you tie a weight
> to a piece of string and whirl it round your head, you can feel a force
> acting outwards on your hand.

Newton's Laws state that a moving item will - if left to itself - travel in
a straight line. The force *you* apply via the string makes it go round in
a circle. Stop applying that force are it will no longer circle you.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html

Jim Lesurf <noise@audiomisc.co.uk> wrote:

> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
> > I was always confused when centrifugal force was described as fictional
> > because it can definitely be felt and demonstrated. If you tie a weight
> > to a piece of string and whirl it round your head, you can feel a force
> > acting outwards on your hand.
>
> Newton's Laws state that a moving item will - if left to itself - travel in
> a straight line. The force *you* apply via the string makes it go round in
> a circle. Stop applying that force are it will no longer circle you.
>
> Jim
>

<https://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law>

Newton's Third Law

"For every action, there is an equal and opposite reaction."

"The statement means that in every interaction, there is a pair of
forces acting on the two interacting objects. The size of the forces on
the first object equals the size of the force on the second object. The
direction of the force on the first object is opposite to the direction
of the force on the second object. Forces always come in pairs - equal
and opposite action-reaction force pairs."

Q: If centripetal force is real, what is its Third Law counterpart?
Is it real?

--
^Ï^ <https://youtu.be/_kqytf31a8E>

My pet rock Gordon just is.

On 22/02/2022 14:42, Sn!pe wrote:
> Jim Lesurf <noise@audiomisc.co.uk> wrote:
>
>> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
>>> I was always confused when centrifugal force was described as fictional
>>> because it can definitely be felt and demonstrated. If you tie a weight
>>> to a piece of string and whirl it round your head, you can feel a force
>>> acting outwards on your hand.
>>
>> Newton's Laws state that a moving item will - if left to itself - travel in
>> a straight line. The force *you* apply via the string makes it go round in
>> a circle. Stop applying that force are it will no longer circle you.
>>
>> Jim
>>
>
> <https://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law>
>
> Newton's Third Law
>
> "For every action, there is an equal and opposite reaction."
>
> "The statement means that in every interaction, there is a pair of
> forces acting on the two interacting objects. The size of the forces on
> the first object equals the size of the force on the second object. The
> direction of the force on the first object is opposite to the direction
> of the force on the second object. Forces always come in pairs - equal
> and opposite action-reaction force pairs."
>
> Q: If centripetal force is real, what is its Third Law counterpart?
> Is it real?
>
When you whirl the string around there are 2 forces*. One is the string
pulling the object. The other is the string pulling you. They are
equal and opposite.

*from the tension in the string. Let's leave aside gravity, air
resistance, interaction of damp string with the earth's magnetic field,
the effects of last night's curry, ...

--
Robin
reply-to address is (intended to be) valid

Robin <rbw@outlook.com> wrote:

> On 22/02/2022 14:42, Sn!pe wrote:
> > Jim Lesurf <noise@audiomisc.co.uk> wrote:
> >
> >> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
> >>> I was always confused when centrifugal force was described as fictional
> >>> because it can definitely be felt and demonstrated. If you tie a weight
> >>> to a piece of string and whirl it round your head, you can feel a force
> >>> acting outwards on your hand.
> >>
> >> Newton's Laws state that a moving item will - if left to itself - travel in
> >> a straight line. The force *you* apply via the string makes it go round in
> >> a circle. Stop applying that force are it will no longer circle you.
> >>
> >> Jim
> >>
> >
> > <https://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law>
> >
> > Newton's Third Law
> >
> > "For every action, there is an equal and opposite reaction."
> >
> > "The statement means that in every interaction, there is a pair of
> > forces acting on the two interacting objects. The size of the forces on
> > the first object equals the size of the force on the second object. The
> > direction of the force on the first object is opposite to the direction
> > of the force on the second object. Forces always come in pairs - equal
> > and opposite action-reaction force pairs."
> >
> > Q: If centripetal force is real, what is its Third Law counterpart?
> > Is it real?
> >
>
> When you whirl the string around there are 2 forces*. One is the string
> pulling the object. The other is the string pulling you. They are
> equal and opposite.
>
> *from the tension in the string.
>

Therefore 'Centrifugal Force' is real, not imaginary. QED

>
> Let's leave aside gravity, air resistance, interaction of damp string with
> the earth's magnetic field, the effects of last night's curry, ...
>

Oh, gladly. I would not want to inflict last night's curry on anybody.

--
^Ï^ <https://youtu.be/_kqytf31a8E>

My pet rock Gordon just is.

On 22/02/2022 16:41, Sn!pe wrote:
> Robin <rbw@outlook.com> wrote:
>
>> On 22/02/2022 14:42, Sn!pe wrote:
>>> Jim Lesurf <noise@audiomisc.co.uk> wrote:
>>>
>>>> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
>>>>> I was always confused when centrifugal force was described as fictional
>>>>> because it can definitely be felt and demonstrated. If you tie a weight
>>>>> to a piece of string and whirl it round your head, you can feel a force
>>>>> acting outwards on your hand.
>>>>
>>>> Newton's Laws state that a moving item will - if left to itself - travel in
>>>> a straight line. The force *you* apply via the string makes it go round in
>>>> a circle. Stop applying that force are it will no longer circle you.
>>>>
>>>> Jim
>>>>
>>>
>>> <https://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law>
>>>
>>> Newton's Third Law
>>>
>>> "For every action, there is an equal and opposite reaction."
>>>
>>> "The statement means that in every interaction, there is a pair of
>>> forces acting on the two interacting objects. The size of the forces on
>>> the first object equals the size of the force on the second object. The
>>> direction of the force on the first object is opposite to the direction
>>> of the force on the second object. Forces always come in pairs - equal
>>> and opposite action-reaction force pairs."
>>>
>>> Q: If centripetal force is real, what is its Third Law counterpart?
>>> Is it real?
>>>
>>
>> When you whirl the string around there are 2 forces*. One is the string
>> pulling the object. The other is the string pulling you. They are
>> equal and opposite.
>>
>> *from the tension in the string.
>>
>
> Therefore 'Centrifugal Force' is real, not imaginary. QED

Neither of the 2 forces above is the mythical "centrifugal force". See
the site you quoted above:

https://www.physicsclassroom.com/class/circles/Lesson-1/The-Forbidden-F-Word

--
Robin
reply-to address is (intended to be) valid

Robin <rbw@outlook.com> wrote:

> On 22/02/2022 16:41, Sn!pe wrote:
> > Robin <rbw@outlook.com> wrote:
> >
> >> On 22/02/2022 14:42, Sn!pe wrote:
> >>> Jim Lesurf <noise@audiomisc.co.uk> wrote:
> >>>
> >>>> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
> >>>>> I was always confused when centrifugal force was described as fictional
> >>>>> because it can definitely be felt and demonstrated. If you tie a weight
> >>>>> to a piece of string and whirl it round your head, you can feel a force
> >>>>> acting outwards on your hand.
> >>>>
> >>>> Newton's Laws state that a moving item will - if left to itself -
> >>>> travel in a straight line. The force *you* apply via the string makes
> >>>> it go round in a circle. Stop applying that force are it will no
> >>>> longer circle you.
> >>>>
> >>>> Jim
> >>>>
> >>>
> >>> <https://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law>
> >>>
> >>> Newton's Third Law
> >>>
> >>> "For every action, there is an equal and opposite reaction."
> >>>
> >>> "The statement means that in every interaction, there is a pair of
> >>> forces acting on the two interacting objects. The size of the forces on
> >>> the first object equals the size of the force on the second object. The
> >>> direction of the force on the first object is opposite to the direction
> >>> of the force on the second object. Forces always come in pairs - equal
> >>> and opposite action-reaction force pairs."
> >>>
> >>> Q: If centripetal force is real, what is its Third Law counterpart?
> >>> Is it real?
> >>>
> >>
> >> When you whirl the string around there are 2 forces*. One is the string
> >> pulling the object. The other is the string pulling you. They are
> >> equal and opposite.
> >>
> >> *from the tension in the string.
> >>
> >
> > Therefore 'Centrifugal Force' is real, not imaginary. QED
> >
>
> Neither of the 2 forces above is the mythical "centrifugal force".
> See the site you quoted above:
>
> <https://www.physicsclassroom.com/class/circles/Lesson-1/The-Forbidden-F-Word>
>

Granted. So what, then, is the force experienced by a finger
whirling a weighty object around on a string? The force is
undeniably transmitted by the string, but what is its name?

--
^Ï^ <https://youtu.be/_kqytf31a8E>

My pet rock Gordon just is.

On 22/02/2022 17:06, Sn!pe wrote:

>
> So what, then, is the force experienced by a finger
> whirling a weighty object around on a string? The force is
> undeniably transmitted by the string, but what is its name?
>

How about "the force on your finger that's keeping the weighty object
whirling around on a string rather than flying off in a straight line at
a tangent"?

--
Robin
reply-to address is (intended to be) valid

Robin <rbw@outlook.com> wrote:

> On 22/02/2022 17:06, Sn!pe wrote:
>
> >
> > So what, then, is the force experienced by a finger
> > whirling a weighty object around on a string? The force is
> > undeniably transmitted by the string, but what is its name?
> >
>
> How about "the force on your finger that's keeping the weighty object
> whirling around on a string rather than flying off in a straight line at
> a tangent"?
>

If we set our minds to it I'm sure we could think of something
better than that. How about "centrifugal force"?

--
^Ï^ <https://youtu.be/_kqytf31a8E>

My pet rock Gordon just is.

On 22/02/2022 18:21, Sn!pe wrote:
> Robin <rbw@outlook.com> wrote:
>
>> On 22/02/2022 17:06, Sn!pe wrote:
>>
>>>
>>> So what, then, is the force experienced by a finger
>>> whirling a weighty object around on a string? The force is
>>> undeniably transmitted by the string, but what is its name?
>>>
>>
>> How about "the force on your finger that's keeping the weighty object
>> whirling around on a string rather than flying off in a straight line at
>> a tangent"?
>>
>
> If we set our minds to it I'm sure we could think of something
> better than that. How about "centrifugal force"?
>

I've already told you the "centrifugal force" ain't real. I don't think
I can help you further.

--
Robin
reply-to address is (intended to be) valid

"Jim Lesurf" <noise@audiomisc.co.uk> wrote in message
news:59beb0d629noise@audiomisc.co.uk...
> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
>> I was always confused when centrifugal force was described as fictional
>> because it can definitely be felt and demonstrated. If you tie a weight
>> to a piece of string and whirl it round your head, you can feel a force
>> acting outwards on your hand.
>
> Newton's Laws state that a moving item will - if left to itself - travel
> in
> a straight line. The force *you* apply via the string makes it go round in
> a circle. Stop applying that force are it will no longer circle you.

Sure. And what name to you give to the outward (away from the centre) force
that I experience while swinging the stone around my head, or the one which
causes a light rotating weight to lift up a heavier one on the other end of
the string? Physics needs to acknowledge these, rather than trying to
pretend they don't exist.

"Robin" <rbw@outlook.com> wrote in message
news:7dc991c1-c662-483b-ff15-c208d9af361b@outlook.com...
> On 22/02/2022 18:21, Sn!pe wrote:
>> Robin <rbw@outlook.com> wrote:
>>
>>> On 22/02/2022 17:06, Sn!pe wrote:
>>>
>>>>
>>>> So what, then, is the force experienced by a finger
>>>> whirling a weighty object around on a string? The force is
>>>> undeniably transmitted by the string, but what is its name?
>>>>
>>>
>>> How about "the force on your finger that's keeping the weighty object
>>> whirling around on a string rather than flying off in a straight line at
>>> a tangent"?
>>>
>>
>> If we set our minds to it I'm sure we could think of something
>> better than that. How about "centrifugal force"?
>>
>
> I've already told you the "centrifugal force" ain't real. I don't think I
> can help you further.

You can *say* that it isn't real, but everyday experience would disagree
with you. Just because someone says that black is really white doesn't
automatically make it so.

Robin <rbw@outlook.com> wrote:

> On 22/02/2022 18:21, Sn!pe wrote:
> > Robin <rbw@outlook.com> wrote:
> >
> >> On 22/02/2022 17:06, Sn!pe wrote:
> >>
> >>>
> >>> So what, then, is the force experienced by a finger
> >>> whirling a weighty object around on a string? The force is
> >>> undeniably transmitted by the string, but what is its name?
> >>>
> >>
> >> How about "the force on your finger that's keeping the weighty object
> >> whirling around on a string rather than flying off in a straight line at
> >> a tangent"?
> >>
> >
> > If we set our minds to it I'm sure we could think of something
> > better than that. How about "centrifugal force"?
> >
>
> I've already told you the "centrifugal force" ain't real. I don't think
> I can help you further.
>

Is there not a capacity to do work provided by the imaginary
centrifugal/centripetal force transmitted down the string?
Is that work imaginary? Surely if the work is real, the force
must likewise be real.

--
^Ï^ <https://youtu.be/_kqytf31a8E>

My pet rock Gordon just is.

On 22/02/2022 22:16, NY wrote:

> You can *say* that it isn't real, but everyday experience would disagree
> with you. Just because someone says that black is really white doesn't
> automatically make it so.
>
<grin>

It depends on the dictionary.

One synonym of Black is Dark
One synonym of Dark is Dim
One synonym of Dim is Pale
One synonym of Pale is Light
One synonym of Light is Bright
One synonym of Bright is White

QED :-)

Jim

On 22/02/2022 22:13, NY wrote:
> "Jim Lesurf" <noise@audiomisc.co.uk> wrote in message
> news:59beb0d629noise@audiomisc.co.uk...
>> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
>>> I was always confused when centrifugal force was described as fictional
>>> because it can definitely be felt and demonstrated. If you tie a weight
>>> to a piece of string and whirl it round your head, you can feel a force
>>> acting outwards on your hand.
>>
>> Newton's Laws state that a moving item will - if left to itself - travel
>> in
>> a straight line. The force *you* apply via the string makes it go round in
>> a circle. Stop applying that force are it will no longer circle you.
>
> Sure. And what name to you give to the outward (away from the centre) force
> that I experience while swinging the stone around my head, or the one which
> causes a light rotating weight to lift up a heavier one on the other end of
> the string? Physics needs to acknowledge these, rather than trying to
> pretend they don't exist.

Perhaps it'll turn out to be something like Laithwaite's examination of
gyroscopes.

--

Jeff

On Tue, 22 Feb 2022 22:13:42 -0000, "NY" <me@privacy.invalid> wrote:

>"Jim Lesurf" <noise@audiomisc.co.uk> wrote in message
>news:59beb0d629noise@audiomisc.co.uk...
>> In article <sv1413$tcq$1@dont-email.me>, NY <me@privacy.invalid> wrote:
>>> I was always confused when centrifugal force was described as fictional
>>> because it can definitely be felt and demonstrated. If you tie a weight
>>> to a piece of string and whirl it round your head, you can feel a force
>>> acting outwards on your hand.
>>
>> Newton's Laws state that a moving item will - if left to itself - travel
>> in
>> a straight line. The force *you* apply via the string makes it go round in
>> a circle. Stop applying that force are it will no longer circle you.
>
>Sure. And what name to you give to the outward (away from the centre) force
>that I experience while swinging the stone around my head, or the one which
>causes a light rotating weight to lift up a heavier one on the other end of
>the string? Physics needs to acknowledge these, rather than trying to
>pretend they don't exist.

Satellites in orbit maintain their distance from earth by traveling at
velocity that ensures that the force of gravity towards the earth does
not lower the orbit. There is only that one force, gravity, towards
the earth. Explanation for 11 to 14 years old here:-

https://spark.iop.org/how-do-satellites-stay-orbit

Your misunderstanding should not make it a necessity for physics to
acknowledge non existent forces? Do you still believe in witchcraft?

--
brightside S9

In article <1pns8gn.mmya1e1lt358dN%snipeco.2@gmail.com>, Sn!pe
<snipeco.2@gmail.com> wrote:
> Newton's Third Law

> "For every action, there is an equal and opposite reaction."

> "The statement means that in every interaction, there is a pair of
> forces acting on the two interacting objects. The size of the forces on
> the first object equals the size of the force on the second object. The
> direction of the force on the first object is opposite to the direction
> of the force on the second object. Forces always come in pairs - equal
> and opposite action-reaction force pairs."

> Q: If centripetal force is real, what is its Third Law counterpart? Is
> it real?

You (and the Earth you're standing on) will also orbit around the common
center of mass of you + earth + object on the other end of the string.

You may not notice that the Earth is being moved, though, as it tends to be
somewhat larger in mass than anything you whirl around on a bit of string!
:-)

However if you consider a sub-part of the system what you see is
accelleration. In this case the object you whirl round is being
accellerated towards the center of its rotation, so goes around you.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 22/02/2022 22:16, NY wrote:
> "Robin" <rbw@outlook.com> wrote in message
> news:7dc991c1-c662-483b-ff15-c208d9af361b@outlook.com...
>> On 22/02/2022 18:21, Sn!pe wrote:

>>> If we set our minds to it I'm sure we could think of something
>>> better than that.  How about "centrifugal force"?
>>>
>>
>> I've already told you the "centrifugal force" ain't real. I don't
>> think I can help you further.
>
> You can *say* that it isn't real, but everyday experience would disagree
> with you. Just because someone says that black is really white doesn't
> automatically make it so.

What about suction? A vacuum doesn't suck. A vacuum isn't anything, so
how can it suck?

Things *seem* to be hard, though, in fact, they are made of atoms which
are mostly empty space. They seem to be hard due to the electrostatic
repulsion between their electron fields.

--
Max Demian