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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

Why Do We Change the Clocks Twice a Year? | Wonderopolis - 0 views

wonderopolis.org/...change-the-clocks-twice-a-year

change of hours

shared by marino5856 on 14 Nov 14 - No Cached
  • it’s Daylight Saving Time! Daylight Saving Time (or “Summer Time,” as it’s known in many parts of the world) was created to make better use of the long sunlight hours of the summer. By “springing” clocks forward an hour in March, we move an hour of daylight from the morning to the evening. On the first Sunday in November, we “fall back” and rewind our clocks to return to Standard Time.
    • marino5856
      marino5856 on 14 Nov 14
       
      the hour changes to save daylight and light because like we have the sun light we don't need to waste la light. It changes in summer to have more light when it is getting night and in october again so that it is more dark because in winter we don't need so much the light.
marino5856

World Clock: Time in the 24 World Time Zones - 0 views

www.elbertwade.com/page142.html

world time zones

shared by marino5856 on 10 Nov 14 - No Cached
    • marino5856
      marino5856 on 10 Nov 14
       
      There are actually 23hr and 59 minutes so they say it is 24 hours. The p.m starts again in one but this is how we count them: 13=1 pm, 14=2 pm 15= 3pm 16= 4 pm 17= 5 pm 18= 6 pm 19= 7 pm 20 =8 pm 21 = 9 pm 22= 10 pm 23 =11 pm. Pm is 23:59:59. AFter this its starts all over again.
  • At Noon, the 12-Hour clock repeats the same hour numbers but as PMAt Noon, the 24-Hour clock keeps adding hour numbers: 13 = 1 PM; 14 = 2 PM; 15 = 3 PM; 16 = 4 PM; 17 = 5 PM; 18 = 6 PM; 19 = 7 PM; 20 = 8 PM; 21 = 9 PM; 22 = 10 PM; 23 = 11 PM through 23:59:59 -- then starts over at 00:00:00 (Midnight)On both clocks, the minutes and seconds are exactly the same
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

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.
marino5856

Why are there 24 hours in a day? › Ask an Expert (ABC Science) - 0 views

www.abc.net.au/...3364432.htm

day hours

shared by marino5856 on 31 Oct 14 - No Cached
  • "The origin of our time system of 24 hours in a day with each hour subdivided into 60 minutes and then 60 seconds is complex and interesting," says Dr Nick Lomb, consultant curator of astronomy, from the Sydney Observatory.
  • Our 24-hour day comes from the ancient Egyptians who divided day-time into 10 hours they measured with devices such as shadow clocks, and added a twilight hour at the beginning and another one at the end of the day-time, says Lomb.
  • "Night-time was divided in 12 hours, based on the observations of stars. The Egyptians had a system of 36 star groups called 'decans' — chosen so that on any night one decan rose 40 minutes after the previous one.
    • marino5856
      marino5856 on 04 Nov 14
       
      The 24 hours has been invented by the egyptians. They first divided it into 10 hours but then they divided it in 12 because of the twilight. So night time was divide in 12 hours because they wanted to see the stars in the night and also that there would be light in the day.
  • ...3 more annotations...
  • The subdivision of hours and minutes into 60 comes from the ancient Babylonians who had a predilection for using numbers to the base 60. For example, III II (using slightly different strokes) meant three times 60 plus two or 182.
  • "We have retained from the Babylonians not only hours and minutes divided into 60, but also their division of a circle into 360 parts or degrees," says Lomb.
  • While each country has (in broad terms) historically had distinct measurements for distance, weights etc the method of splitting the day into 24 hours, one hour into 60 mins and one minute into 60 seconds seems to be the only one in use, and indeed to me the only one I know of. This non-metric measurement of time is far from ideal, but what other comparably accurate methods have been used historically?
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

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

Ever wonder why a day has 24 hours and a minute has 60 seconds - OMG Facts - The World'... - 0 views

www.omgfacts.com/...rs-and-a-minute-has-60-seconds

facts world of 24 hours

shared by marino5856 on 07 Nov 14 - No Cached
  • Egyptians (who used base 12) developed a sundial which looked like a T-shaped bar placed in the ground with would divide the time between sunrise and sunset into 12 parts. Because of the seasonal change in the length of time between sunrise and sunset, summer hours were longer than winter hours! Historians theorize that the importance of 12 is based on the number of finger joints on each hand (not counting the thumb) or the number of lunar cycles in a year. The division of the night into 12 parts was achieved by Egyptian astronomers who observed the appearance of 12 key stars in the night sky. Out of these divisions was born the concept of a 24-hour day. However, seasonal hour length was used for many centuries, and fixed hours became common only after the appearance of mechanical clocks in 14th century Europe!
    • marino5856
      marino5856 on 07 Nov 14
       
      The egyptians  divided the night into 12 hours. So know the people are used t have 24 hours in a day. Many people think it was born like that but it wasn't the egyptians divided the night into 12 hours and also the day into 12 hours. That is 24 hours in total of the day.
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