"Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."

Not exactly an aha moment here...needs a better explanation.

https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/

On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs wrote:
> "Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."
>
> Not exactly an aha moment here...needs a better explanation.
>
> https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/

Well, if you consider the first quadrant of the rotation of the quarter (I was
about to say the first quarter rotation, but that's just... confusing) you see
George doing a headstand...

On Wednesday, June 21, 2023 at 5:47:05 PM UTC-4, whit3rd wrote:
> On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs wrote:
> > "Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."
> >
> > Not exactly an aha moment here...needs a better explanation.
> >
> > https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
> Well, if you consider the first quadrant of the rotation of the quarter (I was
> about to say the first quarter rotation, but that's just... confusing) you see
> George doing a headstand...

If the outer heads up George starts out a the 12 o' clock on the inner quarter, by the time it rolls around to the 6 o'clock, the outer George is back to its original orientation. So that's already one revolution at the halfway point.

On Wednesday, June 21, 2023 at 6:24:54 PM UTC-4, Fred Bloggs wrote:
> On Wednesday, June 21, 2023 at 5:47:05 PM UTC-4, whit3rd wrote:
> > On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs wrote:
> > > "Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."
> > >
> > > Not exactly an aha moment here...needs a better explanation.
> > >
> > > https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
> > Well, if you consider the first quadrant of the rotation of the quarter (I was
> > about to say the first quarter rotation, but that's just... confusing) you see
> > George doing a headstand...
> If the outer heads up George starts out a the 12 o' clock on the inner quarter, by the time it rolls around to the 6 o'clock, the outer George is back to its original orientation. So that's already one revolution at the halfway point.

Yeah, where's the problem? When moving coin reaches the top again, it has rotated twice.

--

Rick C.

- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209

On Thursday, June 22, 2023 at 4:15:56 AM UTC-4, Ricky wrote:
> On Wednesday, June 21, 2023 at 6:24:54 PM UTC-4, Fred Bloggs wrote:
> > On Wednesday, June 21, 2023 at 5:47:05 PM UTC-4, whit3rd wrote:
> > > On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs wrote:
> > > > "Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."
> > > >
> > > > Not exactly an aha moment here...needs a better explanation.
> > > >
> > > > https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
> > > Well, if you consider the first quadrant of the rotation of the quarter (I was
> > > about to say the first quarter rotation, but that's just... confusing) you see
> > > George doing a headstand...
> > If the outer heads up George starts out a the 12 o' clock on the inner quarter, by the time it rolls around to the 6 o'clock, the outer George is back to its original orientation. So that's already one revolution at the halfway point.
> Yeah, where's the problem? When moving coin reaches the top again, it has rotated twice.

Care to explain how it does that by rolling a distance of one circumference, which is just one revolution? If you can't express yourself using standard terminology, don't bother.

>
> --
>
> Rick C.
>
> - Get 1,000 miles of free Supercharging
> - Tesla referral code - https://ts.la/richard11209

On 22/06/2023 13:05, Fred Bloggs wrote:
> On Thursday, June 22, 2023 at 4:15:56 AM UTC-4, Ricky wrote:
>> On Wednesday, June 21, 2023 at 6:24:54 PM UTC-4, Fred Bloggs
>> wrote:
>>> On Wednesday, June 21, 2023 at 5:47:05 PM UTC-4, whit3rd wrote:
>>>> On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs
>>>> wrote:
>>>>> "Coins, testing errors and planetary motion—it’s enough to
>>>>> make anyone’s head spin."
>>>>>
>>>>> Not exactly an aha moment here...needs a better explanation.
>>>>>
>>>>> https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
>>>>
>>>>>
Well, if you consider the first quadrant of the rotation of the quarter
(I was
>>>> about to say the first quarter rotation, but that's just...
>>>> confusing) you see George doing a headstand...

>>> If the outer heads up George starts out a the 12 o' clock on the
>>> inner quarter, by the time it rolls around to the 6 o'clock, the
>>> outer George is back to its original orientation. So that's
>>> already one revolution at the halfway point.

>> Yeah, where's the problem? When moving coin reaches the top again,
>> it has rotated twice.
>
> Care to explain how it does that by rolling a distance of one
> circumference, which is just one revolution? If you can't express
> yourself using standard terminology, don't bother.

It is simple enough if you look at it the right way.

Starting from 12 O'clock vertical as reference zero, when the point of
contact has moved around by an angle A, the coin in contact with the
central coin has also rotated around by an angle A *relative* to the
line through the point of contact (which is at an angle A to the
vertical). This holds true for any angle A including pi and 2pi.

IOW outer coin moves by rolling along the edge so that it rotates by 2A
for every A the point of contact moves around the inner coin.

--
Martin Brown

On Thursday, June 22, 2023 at 8:05:25 AM UTC-4, Fred Bloggs wrote:
> On Thursday, June 22, 2023 at 4:15:56 AM UTC-4, Ricky wrote:
> > On Wednesday, June 21, 2023 at 6:24:54 PM UTC-4, Fred Bloggs wrote:
> > > On Wednesday, June 21, 2023 at 5:47:05 PM UTC-4, whit3rd wrote:
> > > > On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs wrote:
> > > > > "Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."
> > > > >
> > > > > Not exactly an aha moment here...needs a better explanation.
> > > > >
> > > > > https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
> > > > Well, if you consider the first quadrant of the rotation of the quarter (I was
> > > > about to say the first quarter rotation, but that's just... confusing) you see
> > > > George doing a headstand...
> > > If the outer heads up George starts out a the 12 o' clock on the inner quarter, by the time it rolls around to the 6 o'clock, the outer George is back to its original orientation. So that's already one revolution at the halfway point.
> > Yeah, where's the problem? When moving coin reaches the top again, it has rotated twice.
> Care to explain how it does that by rolling a distance of one circumference, which is just one revolution? If you can't express yourself using standard terminology, don't bother.

I'd like to know what is wrong with you. The coin rolls a distance equal to its circumference, so that's one turn. It also travels around the other coin, so that's another turn. 1 + 1 = 2

Is that "standard" enough for you?

--

Rick C.

+ Get 1,000 miles of free Supercharging
+ Tesla referral code - https://ts.la/richard11209

On June 22, Fred Bloggs wrote:
>> Yeah, where's the problem? When moving coin reaches the top again, it has rotated twice.
>
> Care to explain how it does that by rolling a distance of one circumference, which is just one revolution?

How many times does it rotate, seen from the center
of the stationary coin?

"It's all relative"... somebody once said ...

--
Rich

On Thursday, June 22, 2023 at 3:14:35 PM UTC-4, Ricky wrote:
> On Thursday, June 22, 2023 at 8:05:25 AM UTC-4, Fred Bloggs wrote:
> > On Thursday, June 22, 2023 at 4:15:56 AM UTC-4, Ricky wrote:
> > > On Wednesday, June 21, 2023 at 6:24:54 PM UTC-4, Fred Bloggs wrote:
> > > > On Wednesday, June 21, 2023 at 5:47:05 PM UTC-4, whit3rd wrote:
> > > > > On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs wrote:
> > > > > > "Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."
> > > > > >
> > > > > > Not exactly an aha moment here...needs a better explanation.
> > > > > >
> > > > > > https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
> > > > > Well, if you consider the first quadrant of the rotation of the quarter (I was
> > > > > about to say the first quarter rotation, but that's just... confusing) you see
> > > > > George doing a headstand...
> > > > If the outer heads up George starts out a the 12 o' clock on the inner quarter, by the time it rolls around to the 6 o'clock, the outer George is back to its original orientation. So that's already one revolution at the halfway point.
> > > Yeah, where's the problem? When moving coin reaches the top again, it has rotated twice.
> > Care to explain how it does that by rolling a distance of one circumference, which is just one revolution? If you can't express yourself using standard terminology, don't bother.
> I'd like to know what is wrong with you. The coin rolls a distance equal to its circumference, so that's one turn. It also travels around the other coin, so that's another turn. 1 + 1 = 2
>
> Is that "standard" enough for you?

Standard word salad.

>
> --
>
> Rick C.
>
> + Get 1,000 miles of free Supercharging
> + Tesla referral code - https://ts.la/richard11209

On Friday, June 23, 2023 at 4:36:09 PM UTC-4, RichD wrote:
> On June 22, Fred Bloggs wrote:
> >> Yeah, where's the problem? When moving coin reaches the top again, it has rotated twice.
> >
> > Care to explain how it does that by rolling a distance of one circumference, which is just one revolution?
> How many times does it rotate, seen from the center
> of the stationary coin?

From the perspective of a human eye watching the process and fixated on the moving coin, and what is usually considered a revolution...

>
> "It's all relative"... somebody once said ...
>
> --
> Rich

Fred Bloggs <bloggs.fredbloggs.fred@gmail.com> writes:
> Care to explain how it does that by rolling a distance of one
> circumference, which is just one revolution? If you can't express
> yourself using standard terminology, don't bother.

It goes around once because of the distance travelled (or more times, if
the coin is smaller) plus one additional rotation because the path it's
travelling, itself loops around once.

On Friday, June 23, 2023 at 6:41:55 PM UTC-4, Fred Bloggs wrote:
> On Thursday, June 22, 2023 at 3:14:35 PM UTC-4, Ricky wrote:
> > On Thursday, June 22, 2023 at 8:05:25 AM UTC-4, Fred Bloggs wrote:
> > > On Thursday, June 22, 2023 at 4:15:56 AM UTC-4, Ricky wrote:
> > > > On Wednesday, June 21, 2023 at 6:24:54 PM UTC-4, Fred Bloggs wrote:
> > > > > On Wednesday, June 21, 2023 at 5:47:05 PM UTC-4, whit3rd wrote:
> > > > > > On Wednesday, June 21, 2023 at 3:43:13 AM UTC-7, Fred Bloggs wrote:
> > > > > > > "Coins, testing errors and planetary motion—it’s enough to make anyone’s head spin."
> > > > > > >
> > > > > > > Not exactly an aha moment here...needs a better explanation.
> > > > > > >
> > > > > > > https://www.scientificamerican.com/article/the-sat-problem-that-everybody-got-wrong/
> > > > > > Well, if you consider the first quadrant of the rotation of the quarter (I was
> > > > > > about to say the first quarter rotation, but that's just... confusing) you see
> > > > > > George doing a headstand...
> > > > > If the outer heads up George starts out a the 12 o' clock on the inner quarter, by the time it rolls around to the 6 o'clock, the outer George is back to its original orientation. So that's already one revolution at the halfway point.
> > > > Yeah, where's the problem? When moving coin reaches the top again, it has rotated twice.
> > > Care to explain how it does that by rolling a distance of one circumference, which is just one revolution? If you can't express yourself using standard terminology, don't bother.
> > I'd like to know what is wrong with you. The coin rolls a distance equal to its circumference, so that's one turn. It also travels around the other coin, so that's another turn. 1 + 1 = 2
> >
> > Is that "standard" enough for you?
> Standard word salad.

Meaning, you don't understand it at all. Thank you for admitting that. It's big of you.

--

Rick C.

-- Get 1,000 miles of free Supercharging
-- Tesla referral code - https://ts.la/richard11209

On June 23, Fred Bloggs wrote:
>>>> where's the problem? When moving coin reaches the top again, it has rotated twice.
>
>>> Care to explain how it does that by rolling a distance of one circumference,
>>> which is just one revolution?
>
>> How many times does it rotate, seen from the center of the stationary coin?
>
> From the perspective of a human eye watching the process and fixated on the moving coin,

Where is this human eye?

> and what is usually considered a revolution...

How many times does the moon rotate, in one month,
viewed from the earth?

--
Rich

On Saturday, June 24, 2023 at 3:37:44 PM UTC-4, RichD wrote:
> On June 23, Fred Bloggs wrote:
> >>>> where's the problem? When moving coin reaches the top again, it has rotated twice.
> >
> >>> Care to explain how it does that by rolling a distance of one circumference,
> >>> which is just one revolution?
> >
> >> How many times does it rotate, seen from the center of the stationary coin?
> >
> > From the perspective of a human eye watching the process and fixated on the moving coin,
> Where is this human eye?

It's where you're sitting to view that diagram.

> > and what is usually considered a revolution...
> How many times does the moon rotate, in one month,
> viewed from the earth?

Moon appears stationery as viewed from Earth because its rotational period is about the same as its orbital period.

"The moon orbits the Earth once every 27.322 days. It also takes approximately 27 days for the moon to rotate once on its axis. As a result, the moon does not seem to be spinning but appears to observers from Earth to be keeping almost perfectly still. Scientists call this synchronous rotation."

https://www.space.com/24871-does-the-moon-rotate.html

>
>
> --
> Rich