Y2.00719178K (Mar 05 2007)


log in

Advanced search

Message boards : Technical News : Y2.00719178K (Mar 05 2007)

Previous · 1 · 2 · 3 · 4 · Next
Author Message
Urs EchternachtProject donor
Volunteer tester
Send message
Joined: 15 May 99
Posts: 552
Credit: 53,854,139
RAC: 22,781
Germany
Message 536418 - Posted: 25 Mar 2007, 1:01:57 UTC

Germany just got DST a minute ago when the clock jumped from 1:59.59 to 3:00.00. One hour lost ? I want my time back.
____________
_\|/_
U r s

Odysseus
Volunteer tester
Avatar
Send message
Joined: 26 Jul 99
Posts: 1786
Credit: 3,837,698
RAC: 185
Canada
Message 536507 - Posted: 25 Mar 2007, 2:30:24 UTC - in response to Message 536418.
Last modified: 25 Mar 2007, 2:31:04 UTC

Germany just got DST a minute ago when the clock jumped from 1:59.59 to 3:00.00. One hour lost ? I want my time back.

Just wait until autumn: they’ve only borrowed it … unless they switch to full-time DST before then, in which case you’ll have to move to another country (anywhere tropical is highly likely to stick to standard time) in order to get your hour back. ;)

Metod, S56RKO
Volunteer tester
Send message
Joined: 27 Sep 02
Posts: 309
Credit: 35,517,265
RAC: 10,498
Slovenia
Message 537032 - Posted: 26 Mar 2007, 7:55:42 UTC - in response to Message 536507.

Germany just got DST a minute ago when the clock jumped from 1:59.59 to 3:00.00. One hour lost ? I want my time back.

Just wait until autumn: they’ve only borrowed it …

The sad thing, though, is that there's zero interest rate … :(
____________
Metod ...

Profile Clyde C. Phillips, III
Send message
Joined: 2 Aug 00
Posts: 1851
Credit: 5,955,047
RAC: 0
United States
Message 537198 - Posted: 26 Mar 2007, 18:50:53 UTC

One has to pay one way or another with slow or fast clocks (relative to the Sun). Either light mornings and dark evenings or the reverse. Farther from the equator one is taxed more with the extreme seasonal variation of the length of days and nights. One could have a "midnight Sun" that might set at 1AM or have a dawn at noon where the Sun might rise at 1PM. This would be the extreme combination of being a little south of the Arctic (or north of the Antarctic) Circle and having a good-and-fast clock.
____________

Chris Luth
Volunteer tester
Send message
Joined: 24 Dec 99
Posts: 21
Credit: 59,135
RAC: 0
United States
Message 538625 - Posted: 30 Mar 2007, 10:05:36 UTC - in response to Message 535897.
Last modified: 30 Mar 2007, 10:11:32 UTC


I think I have a 27hour circadian rhythm. If the world changed to a 27hour day I would probably sleep better and we certainly wouldn't have to bother with DST.

I'm with ya here. How many rockets attached to the surface of the earth and fired in the opposite direction of the earth's rotation would it take to slow the day down by three hours? And the bigger question: how much fatter would my scale think I was due to the lower centrifugal force from the slower-spinning Earth? (My guess is that, despite the 1,000 mph the Earth spins at the equator, it's not flinging us out as much as you'd think--after all, I don't feel any more weighed down way up here than I did when I was visiting the homeland of Arecibo in November--and that's more than a 40-degree difference in latitude.)

I'm sure there would be horrendous environmental impacts to doing this, but I know my body clock would be much happier with the longer day. I might finally be able to get a full night's sleep without having to oversleep to get it...

(For the sake of my self-image, I probably shouldn't post such ignorant drivel in the presence of the high proportion of S@Hers who are physicists, but oh well...)
____________

Profile ML1
Volunteer tester
Send message
Joined: 25 Nov 01
Posts: 8574
Credit: 4,234,209
RAC: 752
United Kingdom
Message 538636 - Posted: 30 Mar 2007, 10:55:26 UTC - in response to Message 538625.
Last modified: 30 Mar 2007, 10:56:32 UTC

I think I have a 27hour circadian rhythm. If the world changed to a 27hour day I would probably sleep better and we certainly wouldn't have to bother with DST.

Isn't that just being called a night-owl? Or just normal for geek programmers?

;-)

I'm with ya here. How many rockets attached to the surface of the earth and fired in the opposite direction of the earth's rotation would it take to slow the day down by three hours?

Just wait a while and the moon and tides will do that for you.

Shame however that we'll lose the spectacle of the eclipses.

And the bigger question: how much fatter would my scale think I was due to the lower centrifugal force from the slower-spinning Earth? (My guess is that, despite the 1,000 mph the Earth spins at the equator, it's not flinging us out as much as you'd think

It certainly helps rockets up into orbit!

I'm sure there would be horrendous environmental impacts to doing this,...

I'm not so sure... It's an interesting question as to how the weather would be affected. My initial guess is that we would suffer increased development of rain clouds and stronger storms due to the longer day adding more solar energy into any dark clouds that develop. A good question for over at CPDN...


Cheers,
Martin

____________
See new freedom: Mageia4
Linux Voice See & try out your OS Freedom!
The Future is what We make IT (GPLv3)

William Roeder
Volunteer tester
Avatar
Send message
Joined: 19 May 99
Posts: 69
Credit: 523,414
RAC: 0
United States
Message 538688 - Posted: 30 Mar 2007, 13:34:25 UTC - in response to Message 538636.

And the bigger question: how much fatter would my scale think I was due to the lower centrifugal force from the slower-spinning Earth? (My guess is that, despite the 1,000 mph the Earth spins at the equator, it's not flinging us out as much as you'd think


IIRC you weigh about a KG less at the equator than at the poles, because the Earth is a Oblate spheroid (your further from the center.)

As for the rockets, isn't that like the closed box of flying birds don't weigh less. The rockets pushing the air cancel each other.
____________

1mp0£173
Volunteer tester
Send message
Joined: 3 Apr 99
Posts: 8423
Credit: 356,897
RAC: 0
United States
Message 538706 - Posted: 30 Mar 2007, 16:11:15 UTC - in response to Message 538636.

I think I have a 27hour circadian rhythm. If the world changed to a 27hour day I would probably sleep better and we certainly wouldn't have to bother with DST.

Isn't that just being called a night-owl? Or just normal for geek programmers?

;-)

If you've got a 27 hour cycle, your day is going to slide around the clock.

If you wake up at 9:00pm one night, midnight the next, then 3:00am, then 6:00am, then 9:00am -- by the end of the week you're not a night owl, you're sleeping in.

:-)
____________

Profile Sarge
Volunteer tester
Avatar
Send message
Joined: 25 Aug 99
Posts: 9258
Credit: 1,547,289
RAC: 949
United States
Message 538709 - Posted: 30 Mar 2007, 16:27:25 UTC - in response to Message 527709.

For the record, I simply just pulled out my calculator and came up with the number Y2.00719178K for the title of this thread, which I personally feel is the most elegant, if not also fairly accurate way of depicting this particular event. If this "name" hasn't been used elsewhere before, then I claim all creative rights.


Huh? Not MAPLE, Mathematica, Matlab or Derive?!? LOL.

As for categorizing songs, I have this odd penchant for knowing the exact length of every song in my album collection to the second. This kind of number memory came in handy during my college radio days, like when I needed a song that was, say, exactly 5:48 long to end out my radio shift at exactly three hours. Otherwise, it's a useless skill that I could do without, and as I get older I'm less able to do so (I blame CDs - the song lengths are randomly placed on the packaging if anywhere, unlike record albums which always had them on the album itself). I can't remember phone numbers or famous irrational numbers to the Nth digit. Those are completely random, meaningless values. I only can remember "data" i.e., the cost of something I bought 10 years ago, or the length of a song, etc.

- Matt


Here at the SETI@Home message boards, we do not blame CDs. By now, we all know who/what to blame. ;)
____________
Don't be jealous that I look this good. I am just emulating your favorite right-leaning Ted Nugent. ;)

zoom314Project donor
Avatar
Send message
Joined: 30 Nov 03
Posts: 46827
Credit: 37,001,203
RAC: 2,381
United States
Message 538713 - Posted: 30 Mar 2007, 16:46:44 UTC - in response to Message 538706.

I think I have a 27hour circadian rhythm. If the world changed to a 27hour day I would probably sleep better and we certainly wouldn't have to bother with DST.

Isn't that just being called a night-owl? Or just normal for geek programmers?

;-)

If you've got a 27 hour cycle, your day is going to slide around the clock.

If you wake up at 9:00pm one night, midnight the next, then 3:00am, then 6:00am, then 9:00am -- by the end of the week you're not a night owl, you're sleeping in.

:-)

In which case, I think We have a real ET. ;) LOL
____________
My Facebook, War Commander, 2015

Profile Clyde C. Phillips, III
Send message
Joined: 2 Aug 00
Posts: 1851
Credit: 5,955,047
RAC: 0
United States
Message 538716 - Posted: 30 Mar 2007, 16:56:48 UTC - in response to Message 538625.


I think I have a 27hour circadian rhythm. If the world changed to a 27hour day I would probably sleep better and we certainly wouldn't have to bother with DST.

I'm with ya here. How many rockets attached to the surface of the earth and fired in the opposite direction of the earth's rotation would it take to slow the day down by three hours? And the bigger question: how much fatter would my scale think I was due to the lower centrifugal force from the slower-spinning Earth? (My guess is that, despite the 1,000 mph the Earth spins at the equator, it's not flinging us out as much as you'd think--after all, I don't feel any more weighed down way up here than I did when I was visiting the homeland of Arecibo in November--and that's more than a 40-degree difference in latitude.)

I'm sure there would be horrendous environmental impacts to doing this, but I know my body clock would be much happier with the longer day. I might finally be able to get a full night's sleep without having to oversleep to get it...

(For the sake of my self-image, I probably shouldn't post such ignorant drivel in the presence of the high proportion of S@Hers who are physicists, but oh well...)


That stuff can be figured out. One could calculate the mass of the Earth, its effective radius and, by using E = 1/2*m*v^2, calculate its rotational energy, or mv for its rotational momentum. I believe centrifugal acceleration is v^2 / r. Right now I don't have time to figure it out. The average density of the Earth is about 5.5 grams per cubic centimeter, but there is some mass concentration at the core which would reduce the effective radius a little.

____________

Chris Luth
Volunteer tester
Send message
Joined: 24 Dec 99
Posts: 21
Credit: 59,135
RAC: 0
United States
Message 538752 - Posted: 30 Mar 2007, 19:06:14 UTC - in response to Message 538706.
Last modified: 30 Mar 2007, 19:06:33 UTC


If you've got a 27 hour cycle, your day is going to slide around the clock.

If you wake up at 9:00pm one night, midnight the next, then 3:00am, then 6:00am, then 9:00am -- by the end of the week you're not a night owl, you're sleeping in.

:-)


That is exactly what happens when I'm not working and in school (i.e. no real-world schedules to interfere with my sleep patterns--the first night, I may start to feel tired and therefore go to bed at around, oh, 11:00pm. The next day, I don't really feel tired until 2:00am. The next night, it wouldn't be impossible for me to not feel tired until 5:00am. Given a week, I could actually turn into a (gasp) morning person!
____________

silverdragon33d
Send message
Joined: 17 Mar 03
Posts: 2
Credit: 11,201
RAC: 0
United States
Message 539016 - Posted: 31 Mar 2007, 6:15:41 UTC - in response to Message 538713.

I think I have a 27hour circadian rhythm. If the world changed to a 27hour day I would probably sleep better and we certainly wouldn't have to bother with DST.

Isn't that just being called a night-owl? Or just normal for geek programmers?

;-)

If you've got a 27 hour cycle, your day is going to slide around the clock.

If you wake up at 9:00pm one night, midnight the next, then 3:00am, then 6:00am, then 9:00am -- by the end of the week you're not a night owl, you're sleeping in.

:-)

In which case, I think We have a real ET. ;) LOL

Guess im a ET then, i spend atleast 24 or more hours up and then 6 hours down time. been doing it for years. wierd lol

Odysseus
Volunteer tester
Avatar
Send message
Joined: 26 Jul 99
Posts: 1786
Credit: 3,837,698
RAC: 185
Canada
Message 539023 - Posted: 31 Mar 2007, 6:39:18 UTC - in response to Message 538688.

IIRC you weigh about a KG less at the equator than at the poles, because the Earth is a Oblate spheroid (your further from the center.)

If you’re measuring in kilograms, your “weight” is constant, regardless of where you are—they represent mass.

But at the equator, the combination of the Earth’s rotation with the greater distance from the centre (offset a little by the bulge) reduces the force of gravity by about half a percent as compared to that at the poles. If I weighed myself on a spring-scale calibrated at the North Pole, it would read about 0.3 kg light at the equator. (Note that a balance-beam’s reading would be unchanged, ignoring any temperature or air-pressure effects.)

As for the rockets, isn't that like the closed box of flying birds don't weigh less. The rockets pushing the air cancel each other.

Not the same at all. If rockets needed anything to push against, they wouldn’t work in space. True, the exhaust creates some ‘wind’ in the opposite direction, but most of its work is done at the throat of the nozzle, and the remaining energy is rapidly soaked up by dissipative forces. Moreover, the atmosphere is very fluid, so is incapable of imparting significant momentum to the continents.

Which raises another issue: considering that the mantle is also fluid, albeit extremely viscous, the rockets might have undesirable consequences WRT accelerating “continental drift”, triggering earthquakes and vulcanism at the plate margins.

All we have to do to get a longer day is wait a few million years; the Earth’s rotation is gradually slowing as tidal interactions transfer rotational energy to the Moon’s orbit.

Metod, S56RKO
Volunteer tester
Send message
Joined: 27 Sep 02
Posts: 309
Credit: 35,517,265
RAC: 10,498
Slovenia
Message 539063 - Posted: 31 Mar 2007, 11:48:20 UTC - in response to Message 538625.
Last modified: 31 Mar 2007, 11:53:49 UTC

And the bigger question: how much fatter would my scale think I was due to the lower centrifugal force from the slower-spinning Earth? (My guess is that, despite the 1,000 mph the Earth spins at the equator, it's not flinging us out as much as you'd think--after all, I don't feel any more weighed down way up here than I did when I was visiting the homeland of Arecibo in November--and that's more than a 40-degree difference in latitude.)


Not much. Earth's gravity gives acceleration at roughly 9.81 metres per square second while centripetal force at equator gives acceleration at roughly 0.0338 metres per square second (just took it out of my bc). The later one being 0 at the poles of course. Which is roughly 0.34% or a quarter of a kilogram for average human being.
That's approximately half a pound if a pound is the weight of a pint of beer ;)

[edit]The effect of earth's rotation on weight of a mass is directly proportional to the cosine of latitude. Additionally it causes lateral force on body - pushing it towards equator. This effect, however, is rather small and easily masked off by effect of drinking too many pints of beer ;)
____________
Metod ...

Profile Clyde C. Phillips, III
Send message
Joined: 2 Aug 00
Posts: 1851
Credit: 5,955,047
RAC: 0
United States
Message 539196 - Posted: 31 Mar 2007, 19:42:29 UTC

Near the poles one is closer to the center of the Earth, increasing gravitational attraction. Also there's no or little centrifugal force. Near the equator both centrifugal force and being farther from the center of the Earth diminish what the scales register on a given mass. It's probably this centrifugal force that makes the Earth oblate in the first place. Maybe the degree of oblateness is proportional to the centrifugal force but that is a guess. I remember from an old reference that the polar diameter of Earth is about 7900 miles and the equatorial diameter, 7927 miles.
____________

Profile ML1
Volunteer tester
Send message
Joined: 25 Nov 01
Posts: 8574
Credit: 4,234,209
RAC: 752
United Kingdom
Message 539944 - Posted: 2 Apr 2007, 9:56:08 UTC - in response to Message 539023.
Last modified: 2 Apr 2007, 9:57:32 UTC

If you’re measuring in kilograms, your “weight” is constant, regardless of where you are—they represent mass.

Nearly...

If measuring mass, it doesn't matter what units of mass you use. Measuring in pounds or tons is just as correct as tonnes, kilograms or grams (but don't forget the conversion constants!).

"weight" is "mass" times (opposed) "gravitational attractive force". Mass remains constant whilst your weight depends on how you are attracted to what is supporting you.

"weight" is in effect a special assumed case of "force = mass * acceleration"


Now soon to enjoy a good big lunch!

Cheers,
Martin

____________
See new freedom: Mageia4
Linux Voice See & try out your OS Freedom!
The Future is what We make IT (GPLv3)

Profile Clyde C. Phillips, III
Send message
Joined: 2 Aug 00
Posts: 1851
Credit: 5,955,047
RAC: 0
United States
Message 540089 - Posted: 2 Apr 2007, 19:22:37 UTC

I get 0.03391 m/s^2 centrifugal acceleration at the equator factoring in 366.24 revolutions per year sidereally, or 0.003458 g. 7927/7900 is about 1.003418, which is awfully close to unity plus the centrifugal acceleration in gs. So it's possible that oblateness might have something to do with centrifugal force / gravitational force. I don't know whether trying this on Jupiter or Saturn would work or not. There is the problem of extreme mass variation throughout those planets. If someone is 1/3 percent farther from a mass concentration the gravity is 2/3 percent less due to falloff being as the square of the distance. This might suggest that someone weighing 100 kilograms at the poles would weigh only 99 kilograms at the equator (2/3 percent falloff + 1/3 percent centrifugal force). But Earth is not a point mass concentration so this may not be correct. I don't know what a plumb bob does at temperate latitudes. Does it hang exactly vertically? (90 degrees from the horizon). Even the horizon is depressed but (I believe) refracted upward by the air. If a star becomes visible on the horizon it's 34 minutes below the horizon. But is the apparent horizon exactly 90 degrees from the zenith or nadir? The altitude of the eyes changes this, of course.
____________

John McLeod VII
Volunteer developer
Volunteer tester
Avatar
Send message
Joined: 15 Jul 99
Posts: 24789
Credit: 524,053
RAC: 86
United States
Message 540181 - Posted: 2 Apr 2007, 23:53:31 UTC

If I recall correctly (it has been quite a while), as long as the center of mass is a particular distance away, and the object is spherical, it does not matter what size the sphere is as long as the radius of the sphere does not exceed the distance from the center of mass to the nearest point of the other object.

Spherical shells of different mass densities all look like a mass at a single point from outside of the outermost sphere.
____________


BOINC WIKI

Odysseus
Volunteer tester
Avatar
Send message
Joined: 26 Jul 99
Posts: 1786
Credit: 3,837,698
RAC: 185
Canada
Message 540254 - Posted: 3 Apr 2007, 4:00:33 UTC - in response to Message 539944.
Last modified: 3 Apr 2007, 4:01:05 UTC

If you’re measuring in kilograms, your “weight” is constant, regardless of where you are—they represent mass.

Nearly...
If measuring mass, it doesn't matter what units of mass you use. Measuring in pounds or tons is just as correct as tonnes, kilograms or grams (but don't forget the conversion constants!).

No argument here. My point was that kilograms can only measure mass (the existence of the bastard unit “kilograms-force” notwithstanding), not that you can’t measure mass in any other units. OTOH the pound can refer to either mass or force, depending on context. (The poundal, one pound-foot per second per second, is rarely used.)

"weight" is "mass" times (opposed) "gravitational attractive force". Mass remains constant whilst your weight depends on how you are attracted to what is supporting you.

"weight" is in effect a special assumed case of "force = mass * acceleration"

Yes and no. Technically speaking, “weight” should always be a force, but as used in common parlance the term refers to what a physicist would call “mass” at least as often as not. If Alcan finds that a shipment of Jamaican bauxite unloaded at Kitimat is short, I don't think they'd accept the explanation that the weight was correct at the latitude it was shipped from! A silly example, perhaps, but the point is that most of the time we mean by "weight" an invariant property that’s independent of local circumstances, viz mass. Likewise “to weigh” something usually means to determine its mass, although the method used may well involve comparing gravitational forces.

____________

Previous · 1 · 2 · 3 · 4 · Next

Message boards : Technical News : Y2.00719178K (Mar 05 2007)

Copyright © 2014 University of California