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S.NO
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Physical Quantity
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Unit
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1
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Length
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(a) 1 micrometer = 10-6 m
(b) 1 angstrom =10 -10 m
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2
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Mass
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(a) 1 metric ton = 103 kg
(b) 1 pound = 0.4537 kg
(c) 1 amu = 1.66 x10-23 kg
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3
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Volume
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1 liter = 10-32 m
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4
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force
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(a) 1 dyne = 10-5 N
(b) 1 kgf = 9.81 N
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5
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pressure
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(a) 1 kgfm2
= 9.81Nm-2
(b) 1 mm of Hg = 133 Nm-2
(c) 1 Pascal = 1 Nm-2
(d) 1 atmosphere pressure = 76 cm of Hg = 1.01 x 105 Pascal
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6
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Work and energy
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(a) 1 erg =10-7J
(b) 1 kgf-m = 9.81 J
(c) 1 kWh = 3.6 x 106 J
(d) 1 eV = 1.6 x 10-19 J
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Some Practical Units
1. 1 Fermi =10-15 m
2. 1 X-ray unit = 10-13 m
3. 1 astronomical unit = 1.49 x 1011 m (average distance between sun and earth)
4. 1 light year = 9.46 x 1015 m
5. 1 parsec = 3.08 x 1016 m = 3.26 light year
