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Time
The length of a second is a human convention. In 1820, a second
was defined as 1/86 400 of a day. The logic being that (0.0K).
Here at the turn of the millenium, the length of one second
is defined as the time it takes for 9 192 631 700 oscillations
of the radiation emitted/absorbed by the atoms of cesium-133.
| When
talking about clocks, accuracy is the name of the game. (0.0K) |
Clock
To measure time, you need a clock. Most of us carry around compact
quartz clocks on our wrist. Suppose that your wrist clock lost
or gained one second every thousand seconds. Then your time
would be off by 43 minutes in one month. | (1.0K) |
(0.0K) | A
good quartz watch is accurate to the millionth of a second.
In one year, how far off would this watch be? Use scientific
notation and the factor-label method in your calculations.
|
NIST-7
The clockmakers at the National Institute of Standards and Technology
in Boulder, Colorado would like to offer you a clock, maybe
for your hallway. The clock, called the NIST-7, will cost you
$50 000, but you will get a clock that is accurate to the fourteenth
decimal place. | (14.0K) http://www.ubr.com/clocks/nist
/nistfstd/n7_300.gif |
(0.0K) | How
old will you be when you need to call the NIST people to report
that your clock is off by one second? NIST-7 uses oscillations
of radiation that are emitted by cesium-133 to keep time. When
the clock is one second off, how many oscillations will have
occured? Use scientific notation and the factor-label method
in your calculations. |
(1.0K) | To
learn more about the goings-on at NIST, visit http://physics.nist.gov/News
/Update/930503.html, http://physics.nist.gov/GenInt/Time/time.html,
or http://www.bldrdoc.gov/timefreq/.
Clicking will launch a new window. |
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