units and measurement, plus one first chapter introduction

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Units and Measurements
Presented by
Sana

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Lets talk about
■ Measurment of length
■ Measurement of mass
■ Measurment of time
■ Accuracy and precision
■ Errors
■ Significant figures
■ Dimensions

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SLIDESMANIA.COM
Measurment of length

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Parallax method
The effect whereby the position or direction of an object
appears to differ when viewed from different positions.

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SLIDESMANIA.COM
Range of length
Atom
1 fermi = 10-15 m
1 Angstorm = 10-10m
Astronomical Unit (AU)
1 AU = distance between Sun &
Earth
1 AU = 1.496*10¹¹m
Light-year
It is the distance light travels in
one Earth year.
ly = 9.46*1015
m

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SLIDESMANIA.COM
The moon is observed from two diametrically opposite points A and B on
Earth.The angle subtended at the moon by the two directions of observation
is 1° 54'.Given the diameter of the Earth to be about 1.276 * 10 ^ 7 m,
compute the distance of the moon from the Earth.
? The Sun's angular diameter is measured to be 1920’’.The distance of the sun
from the earth is 1.496 ×10^11 m? What is the diameter of the sun?

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SLIDESMANIA.COM
For very heavy object we use gravitational method.
For very light object we use mass spectrograph
1 AMU = Mass of 1/12 of C-12 atom
F
Measurement of Mass

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