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marino5856

hour (unit of time) -- Encyclopedia Britannica - 0 views

global.britannica.com/...hour

hours 24 not 60

shared by marino5856 on 31 Oct 14 - No Cached
  • in timekeeping
  • 3,600 seconds, now defined in terms of radiation emitted from atoms of the element cesium under specified conditions. The hour was formerly defined as the 24th part of a mean solar day—i.e., of the average period of rotation of the Earth relative to the Sun. The hour of sidereal time, 1/24 of the Earth’s rotation period relative to the stars, was about 10 seconds shorter than the hour of mean solar time.
    • marino5856
      marino5856 on 05 Nov 14
       
      It also has 24 hours the earth because in the system of the egyptians it said that it also has 24 hours because of the earth spinning.
  • In even earlier systems of timekeeping, an hour was 1/12 of a period of daylight or darkness—hence, variable in length with seasonal changes in the length of day and night. The custom of dividing the cycle of day and night into 24 periods seems to have originated with the ancient Egyptians.
lobo5879

Five Stages Of Sleep ... Sleep Cycles Explained - 2 views

www.better-sleep-better-life.com/five-stages-of-sleep.html

stages sleep

shared by lobo5879 on 03 Nov 14 - No Cached
  • Stage 1This is the lightest stage of sleep, the transition phase, where you feel yourself drifting off. If you were to forget about the alarm clock and allow yourself to wake up naturally, Stage 1 sleep would be the last stage before you fully wake up. You don't spend too much time in Stage 1 sleep, typically five to 10 minutes, just enough to allow your body to slow down and your muscles to relax.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      The stage 1 of sleep is when you are starting to relax your muscles and start to sleep. This stages is not very long it is about 5 to ten minutes. This stage is when you wake up more quickly for example if someone touches you you will easily wake up.
  • Stage 2The second stage of sleep is still considered light sleep. Your brain activity starts to slow down, as well as your heart rate and breathing. Your body temperature falls a little and you're beginning to reach a state of total relaxation in preparation for the deeper sleep to come.
  • Stage 3Stage 3 sleep is the start of deep sleep, also known as slow wave sleep. During stage 3, your brain waves are slow "delta waves," although there may still be short bursts of faster of brain activity (also known as beta-waves). If you were to get awakened suddenly during this stage, you would be groggy and confused, and find it difficult to focus at first.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      this stage is when your body is finishing to relax and example is: if someone trys to wake you up you would be confused and do not know what is happening because you were already finishing to completely relax
  • ...3 more annotations...
  • Stage 4Of the five stages of sleep, this is the one when you experience your deepest sleep of the night. Your brain only shows delta-wave (slow wave) activity, and it's difficult to wake someone up when they're in Stage 4 of sleep.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      this stage i when you are more hardly to be awaken. In this stage is when you start to dream and this stage is when the kids start having nightmares
  • It's during Stage 4 sleep that children are most likely to suffer from bedwetting or sleep terrors. Stages 3 and 4 can last anywhere from 5 - 15 minutes each, but the first deep sleep of the night is more likely to be an hour or so. This is the time when the body does most of it's repair work and regeneration.
  • Stage 5 This is the stage of sleep when you dream. It is also referred to as "active sleep" or REM sleep, which stands for the rapid eye movements that characterize Stage 5. During REM sleep, your blood flow, breathing, and brain activity increases. An EEG would show that your brain is about as active as it is when you're awake.Another aspect of Stage 5 sleep is that the muscles in your arms and legs will go through periods of paralysis. Scientists speculate that this may be nature's way of protecting us from acting out our dreams.The first period of REM sleep of the night usually begins about 90 minutes after you start drifting off, and lasts for about 10 minutes. As the night passes, the periods of REM sleep become longer, with the final episode lasting an hour or so.Babies may spend as much as half of the time they're asleep in the REM phase. For a healthy adult, Stage 5 occurs for about 20 to 25% of the time you are sleeping, and decreases with age.Scientists and researchers are continually learning more about the mechanics and physiological effects of sleep, and what happens during the five stages of sleep.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      This stage is when you are completly relaxed and many babies are many time during this tage and adults are abaut 25% of they sleep
    • lobo5879
      lobo5879 on 06 Nov 14
       
      This stage is more dificult to wake up because you are alrady in deep sleep.
marino5856

Curious About Astronomy: Why is a day divided into 24 hours? - 0 views

curious.astro.cornell.edu/question.php

Day divided into 24 hours

shared by marino5856 on 04 Nov 14 - Cached
  • December 2003 answer: It appears that the Egyptians were responsible for the 24 hour day. The Eqyptians were fond of counting in base twelve (instead of base 10 which is commonly used today). This is thought to be because they counted finger joints instead of fingers. Each of your fingers has three joints, so if you count by pointing to finger joints with your thumb you can count to twelve on each hand. This might seem arbitrary, but is actually just a strange as counting in base ten simply because we have ten digits.
    • marino5856
      marino5856 on 04 Nov 14
       
      The egyptians were the ones that were in charge of the 24 hours in a day because they had a system so they found  a counting base in twelve.
  • The Egyptians divided the clock into 12 hours of daytime and 12 hours of night-time (or alternatively 10 hours between sunrise and sunset, an hour for each twilight period and 12 hours of darkness). This is known because of various sundials from the period which have been found to be marked with hours. Interestingly this means that hours started out changing in length with the seasons (as the amount of daylight vs. darkness changes).
    • marino5856
      marino5856 on 04 Nov 14
       
      they divided the clock in 12 hours because 12 in the night and about 10 in the sunrise that it became 12hours so that it is equal.
    • marino5856
      marino5856 on 05 Nov 14
       
      The egyptians divided the clock into 12 hours. 1,2,3,4,5,6,7,8,9,10,11,12 a.m and 1.2.3.4.5.6.7.8.9.10.11.12 p.m so that all the p.m could see the stars and the a.m the sunrise. Like there are 12 a.m and 12 p.m so 12 plus 12 equals24 thats why we have 24 hours in a day.
marino5856

Why is a minute divided into 60 seconds, an hour into 60 minutes, yet there are only 24... - 0 views

www.scientificamerican.com/...me-division-days-hours-minutes

60 minute seconds minutes

shared by marino5856 on 05 Nov 14 - No Cached
  • Thanks to documented evidence of the Egyptians' use of sundials, most historians credit them with being the first civilization to divide the day into smaller parts. The first sundials were simply stakes placed in the ground that indicated time by the length and direction of the resulting shadow. As early as 1500 B.C., the Egyptians had developed a more advanced sundial.
    • marino5856
      marino5856 on 06 Nov 14
       
      Thanks to the duodecimal system. The  egyptians used the system to make counting more easier. Also the number 12 is typically attributed.
  • A T-shaped bar placed in the ground, this instrument was calibrated to divide the interval between sunrise and sunset into 12 parts. This division reflected Egypt's use of the duodecimal system--the importance of the number 12 is typically attributed either to the fact that it equals the number of lunar cycles in a year or the number of finger joints on each hand (three in each of the four fingers, excluding the thumb), making it possible to count to 12 with the thumb.
  • The next-generation sundial likely formed the first representation of what we now call the hour. Although the hours within a given day were approximately equal, their lengths varied during the year, with summer hours being much longer than winter hours
  • ...1 more annotation...
  • Egyptian astronomers also first observed a set of 36 stars that divided the circle of the heavens into equal parts. The passage of night could be marked by the appearance of 18 of these stars, three of which were assigned to each of the two twilight periods when the stars were difficult to view. The period of total darkness was marked by the remaining 12 stars, again resulting in 12 divisions of night (another nod to the duodecimal system).
    • marino5856
      marino5856 on 06 Nov 14
       
      Egyptians noticed that there was 36 stars in each part so they divided that into equal parts 12.
Esteban Cantu

Moons of Jupiter - Wikipedia, the free encyclopedia - 0 views

en.wikipedia.org/...Moons_of_Jupiter

jupiter

shared by Esteban Cantu on 11 Nov 14 - Cached
  • For two decades no additional moons were discovered; but between October 1999 and February 2003, researchers using sensitive ground-based detectors found and later named another 34 moons,
    • Esteban Cantu
      Esteban Cantu on 11 Nov 14
       
      On 1999 to 2003 34 more moons of jupiter were discovered.
  • The moons' physical and orbital characteristics vary widely. The four Galileans are all over 3,100 kilometres (1,900 mi) in diameter; the largest Galilean, Ganymede, is the ninth largest object in the Solar System, after the Sun and seven of the planets (Ganymede being larger than Mercury). All other Jovian moons are less than 250 kilometres (160 mi) in diameter, with most barely exceeding 5 kilometres (3.1 mi). Orbital shapes range from nearly perfectly circular to highly eccentric and inclined, and many revolve in the direction opposite to Jupiter's spin (retrograde motion). Orbital periods range from seven hours (taking less time than Jupiter does to spin around its axis), to some three thousand times more (almost three Earth years).
    • Esteban Cantu
      Esteban Cantu on 14 Nov 14
       
      Ganymede, one of Jupiter's four galilean moons, is bigger than Mercury. 
  • ...1 more annotation...
  • Main group or Galilean moons: Io, Europa, Ganymede and Callisto. They are some of the largest objects in the Solar System outside the Sun and the eight planets in terms of mass and larger than any known dwarf planet, and Ganymede exceeds the planet Mercury in diameter.
    • Esteban Cantu
      Esteban Cantu on 14 Nov 14
       
      4 of Jupiter's moons, the galilean moons, are some of the largest objects in our universe.
lobo5879

Sleep Facts: 20 Facts about Sleep you didn't know ←FACTSlides→ - 1 views

www.factslides.com/s-Sleep

sleep facts

shared by lobo5879 on 31 Oct 14 - No Cached
  • Humans spend a third of their life sleeping. That's about 25 years.
    • lobo5879
      lobo5879 on 05 Nov 14
       
      did you now that humnans spend 25 yeras of theire life and cats spend 70% of ther elofes sleeping
  • The record for the longest period without sleep is 11 days.
    • lobo5879
      lobo5879 on 05 Nov 14
       
      did you know that the record of a humnan without sleping is 11 fays
  • Sleeping less than 7 hours each night reduces your life expectancy.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      did you know that sleping less than 7 hrs evry night can take time of youre life.
  • ...8 more annotations...
  • Some Deaf People Make Sign Language in Their Sleep.
    • lobo5879
      lobo5879 on 05 Nov 14
       
      id you know that the people that cant hear make sign anguege when they are sleeping
  • Before alarm clocks were invented, there were "knocker-ups" who went tapping on client's windows with long sticks until they were awake.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      Did you know that before alarm clockd=s were invented they used to be a person that tapped you on the window to wake you up.
  • It's impossible to sneeze while sleeping.
    • lobo5879
      lobo5879 on 05 Nov 14
       
      Did you know that you cant sleep when you are slepping they say it is imposible
  • Most people can survive for up to 2 months without eating, but people can only live up to 11 days without sleeping.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      did you know that most people can suvive without eating for 2 months and without sleping 11 days
  • Sea otters hold hands when they sleep so they don't drift away from each other.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      did you know that sea otters hold theyre hand while they are slleping so they dont get lost during theyre slep
  • People experience better sleep during the new moon and worse sleep during a full moon, a study found.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      Did you know that people sllep vetter during the new moon than the ful moon
  • Cats sleep for 70% of their lives.
  • Lack of sleep can cause weight gain of 2 pounds (0.9 kg) in under a week.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      did you know that when you sleep a lot you can gain pounds in a week you can gain 2 pounds in a week
lobo5879

Nightmares - 1 views

kidshealth.org/...nightmares.html

nightmares dreams

shared by lobo5879 on 31 Oct 14 - Cached
  • While you sleep, your brain doesn't just turn off. It goes through several sleep stages, including REM (rapid eye movement) sleep. Why do they call it that? Because during this stage of sleep, your eyes move back and forth under your closed eyelids. During REM sleep, you have dreams and sometimes those dreams can be scary or upsetting. About every 90 minutes your brain switches between non-REM sleep and REM sleep. The amount of time spent in REM sleep increases with each sleep cycle through the night. The longest periods of REM sleep occur towards morning. If you wake during this REM stage, it is easier for you to remember what you were dreaming about. That's why your most vivid dreams — and nightmares — occur in the early morning hours.
    • lobo5879
      lobo5879 on 04 Nov 14
       
      People have nightmares because when you are in REM (that stand for rapid eye movement) is when you are starting to have dreams and sumetimes the dreams are upseting thats why they are called nightmares
    • lobo5879
      lobo5879 on 05 Nov 14
       
      and evry 90 minutes youre brain desides to go to REM then without REM
marino5856

Clocks - How Time Works - 1 views

science.howstuffworks.com/...time2.htm

How does the clock works

shared by marino5856 on 31 Oct 14 - No Cached
  • A day consists of two 12-hour periods, for a total of 24 hours. An hour consists of 60 minutes. A minute consists of 60 seconds. Seconds are subdivided on a decimal system into things like "hundredths of a second" or "millionths of a second."
    • marino5856
      marino5856 on 04 Nov 14
       
      There is 24 hours in a day because  they first divided 60 and that equals 12. So 12 plus 12 equals 24 so thats how they had 24 hours in a day.
  • hat's a pretty bizarre way to divide a day up. We divide it in half, then divide the halves by twelfths, then divide the twelfths into sixtieths, then divide by 60 again, and then convert to a decimal system for the smallest increments. It's no wonder children have trouble learning how to tell time.
  • How long is a day? It's the amount of time it takes for the Earth to rotate one time on its axis. But how long does it take the Earth to rotate? That is where things become completely arbitrary. The world has decided to standardize on the following increments:
  • ...3 more annotations...
  • Why are there 24 hours in a day? No one really knows. However, the tradition goes back a long way. Take, for example, this quote from Encyclopedia Britannica:
  • Why are there 60 minutes in an hour and 60 seconds in a minute? Again, it is unclear. It is known, however, that Egyptians once used a calendar that had 12 30-day months, giving them 360 days. This is believed to be the reason why we now divide circles into 360 degrees. Dividing 360 by 6 gives you 60, and 60 is also a base number in the Babylonian math system.
    • marino5856
      marino5856 on 04 Nov 14
       
      The Egyptians had a calendar that has 12 months so that equals 360 day in total. Also science they new that there is 360 days in a year thats why a circle is 360 degrees. The Roman people invented that so that in the clock there is not 24 hours in a clock so there is 12 am and 12pm.
  • What do a.m. and p.m. mean? These abbreviations stand for ante meridiem, before midday, and post meridiem, after midday, and they are a Roman invention. According to Daniel Boorstin in his book The Discoverers, this simple division of the day into two parts was the Romans' first increment of time within a day:
marino5856

Earth's Rotation - 0 views

www.polaris.iastate.edu/...unit3_sub1.htm

earth rotation 24 hours

shared by marino5856 on 07 Nov 14 - No Cached
  • The earth rotates about an imaginary line that passes through the North and South Poles of the planet.  This line is called the axis of rotation.  Earth rotates about this axis once each day (approximately 24 hours).  Although you most likely already knew that fact, there is a slight complication most people are not aware of.
  • More specifically, our rotation period (the time elapsed for one rotation) with respect to the stars  is called a sidereal day.  A sidereal day is 24 sidereal hours, or 23 hours and 56 minutes on a normal clock.  Our clock time is based on the earth's rotation with respect to the sun from solar noon to solar noon.  This is a solar day, and it is divided into 24 hours.  Because Earth travels about 1 / 365 of the way around the sun during one day, there is a small difference between solar time and sidereal time.
    • marino5856
      marino5856 on 07 Nov 14
       
      The earth rotates with axis lines and  there is 24 lines thats why there are 24 hours in a day. The earth time is rotated into 24hours because the earth rotate 1/365 during one day.
jaime5789

BBC Nature - Dinosaurs 'shrank' regularly to become birds - 0 views

www.bbc.co.uk/28563682

shared by jaime5789 on 04 Nov 14 - No Cached
  • Huge meat-eating, land-living dinosaurs evolved into birds by constantly shrinking for over 50 million years, scientists have revealed.
    • jaime5789
      jaime5789 on 04 Nov 14
       
      Gigantic dinosaurs evolved into the small birds we know today! Scientists think that dinosaurs evolved into birds, now people also think that dinosaurs used to have feathers! Big meat eating dinosaurs such as the Spinosaurus and T-Rex may have evolved into the modern birds we know today! 
    • jaime5789
      jaime5789 on 04 Nov 14
       
      Gigantic dinosaurs evolved into the small birds that we see today! Scientists think that dinosaurs evolved into birds, now people also think that dinosaurs used to have feathers! Big meat eating dinosaurs such as the Spinosaurus and T-Rex may have evolved into the modern birds we know today! 
    • jaime5789
      jaime5789 on 04 Nov 14
       
      Gigantic dinosaurs such as the Spinosaurus and T-Rex evolved into the small birds that we see today. Scientists think that dinosaurs evolved into birds, now people also think that dinosaurs used to have feathers! 
    • jaime5789
      jaime5789 on 05 Nov 14
       
      New Paraphrase: Did you know that dinosaurs, such as the Tyrannosaurus Rex and the fearsome Velociraptor became smaller, and after 50 million years, we now think that... 
  • Previous work has shown that theropod dinosaurs, the dinosaur group which included Tyrannosaurus rex and Velociraptor and gave rise to modern birds, must have decreased in size at some point in their evolution into small, agile flyers.
    • jaime5789
      jaime5789 on 04 Nov 14
       
      Now, work has shown that two legged dinosaurs including T-Rex and the fearsome Velociraptor gave birth to the birds we see today!
    • jaime5789
      jaime5789 on 05 Nov 14
       
      The University of Adelaide, wonders a lot about dinosaurs... They found out that dinosaurs such as Spinosaurus and Utahraptor made the birds we know today! 
  • But size changes frequently occurred in dinosaur evolution, so the research team members, led by Mike Lee, from the University of Adelaide, Australia, wanted to find out if the dramatic size reduction associated with the origin of birds was unique. They also wanted to measure the rate of evolution in dinosaurs using a large data set
    • jaime5789
      jaime5789 on 04 Nov 14
       
      Research indicates that dinosaurs constantly changed, the University of Adelaide wants to find out what makes the gigantic size changes? They found out that the evolution by dinosaur is unique and amazing! 
    • jaime5789
      jaime5789 on 04 Nov 14
       
      The University of Adelaide also wants to measure the the frequency of dinosaur evolution!
    • jaime5789
      jaime5789 on 05 Nov 14
       
      The U.O.A (University Of Adelaide) wonders, "how can something so big turn into something so small?" this is due to new eras, and the evolution of dinosaurs & birds!
  • ...9 more annotations...
  • They found that the dinosaur group directly related to birds shrank rapidly from about 200 million years ago.
    • jaime5789
      jaime5789 on 04 Nov 14
       
      Scientists found out that a dinosaur species related to birds shrank in a short time and probably turned into the birds we know today! 
    • jaime5789
      jaime5789 on 05 Nov 14
       
      Dinosaur species related to birds, shrank in a short period of time! We know believe that they turned into the birds that we're familiar with today! 
  • Theropods shrunk 12 times from 163kg (25st 9lb) to 0.8kg (1.8lb), before becoming modern birds.
    • jaime5789
      jaime5789 on 05 Nov 14
       
      Really big dinosaurs started shrinking and their weight decreased slowly..
  • The researchers found theropods were the only dinosaurs to get continuously smaller.
    • jaime5789
      jaime5789 on 05 Nov 14
       
      Scientists now know that the two-legged dinosaur species were the dinosaurs that frequently got smaller! 
  • From this analysis they produced a detailed family tree mapping out the transformation of theropods to their bird descendants.
    • jaime5789
      jaime5789 on 05 Nov 14
       
      We now predit that the two-legged dinosaurs transformed into birds!
  • It traces evolving adaptations and changing body size over time and across dinosaur branches.
    • jaime5789
      jaime5789 on 05 Nov 14
       
      We now think that dinosaurs adapted into transforming into birds little by little! 
  • The researchers concluded that the evolution of the branch of dinosaurs leading to birds was more innovative than other dinosaur lineages.
    • jaime5789
      jaime5789 on 05 Nov 14
       
      We conclude that, dinosaurs probably changed into birds! 
  • this sustained shrinking and accelerated evolution of smaller and smaller body size allowed the ancestors of birds to develop traits which helped them to cope much better than their less evolved dinosaur relatives.
    • jaime5789
      jaime5789 on 07 Nov 14
       
      Dinosaurs were getting smaller they developed traits to survive. 
  • The researchers believe that miniaturisation and the development of bird-like traits had a joint influence on the evolution of the dinosaurs into today's birds. Professor Michael Benton, from the University of Bristol's school of earth sciences, said: "This study means we can't see the origin of birds as a sudden or dramatic event, with a dinosaur becoming a powered flyer overnight. "The functions of each special feature of birds changed over time - feathers first for insulation, and later co-opted for flight; early reductions in body size perhaps for other reasons, and later they were small enough for powered flight; improvements in sense of sight and enlargement of brain - even a small improvement in these is advantageous. "So perhaps it's a long-term trend associated with deputation to a new set of habitats, in the trees, to avoid predation, and to exploit new food resources."
    • jaime5789
      jaime5789 on 07 Nov 14
       
      Researchers now think that the shrinking of the dinosaurs was what developed dinosaurs into todays birds! Professor Michael from the University of Bristol says that we can't study the era of birds, just like that...
    • jaime5789
      jaime5789 on 07 Nov 14
       
      This is a long process that didn't just happen like that, you sleep, you wake up and you're a bird, no! Its a very difficult process! 
  • "Birds evolved through a unique phase of sustained miniaturisation in dinosaurs," Mr Lee said.
    • jaime5789
      jaime5789 on 07 Nov 14
       
      Birds evolved due to the dinosaurs becoming smaller!
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