Page 23 - SM inner class 8.cdr

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The mass of the moon = 735. ´ 10 kg (c) 30001 10. ´ 8 = 30001 ´10 8
Total Mass = 597 10. ´ 24 kg. + 735 10. ´ 22 kg 10000
30001 ´10 8
22
22
´
´
.
= 597 10 2 ´10 kg. + 735 10 kg =
.
10 4
22
= (597 + .35 ) ´10 kg 8 -4
7
´
= 30001 10
22
24
´
´
.
= 604 35 10 kg = 60435 10 kg 4
.
= 30001 ´10 =300010000
Example 15. The radius of sun is 7 10´ 8 m and
6
that of earth is 64. ´ 10 m. Compare the radii 2. Expressing very small Numbers in
of two. scientific Notation
8
Radius of sun 7 ´10 m
Solution: = Example 17. Express each of following number
Radius of Earth 64 ´10 6 in scientific notation:
.
7 ´10 2 700 (i) 0.00004 (ii) 0.000000072
= =
64 64 (iii) 0.00000000621
.
.
=109375 4
.
Solution: (i) 000004. = = 4 ´ 10 - 5
\ Radius of sun is approximately 109 times 10 5
that of Earth. 79 72 ´10 1
.
(ii) 0000000072. = =
Example 16. Write each of the following 10 9 10 9
numbers in usual form. 72 72
.
.
= = = 72 10. ´ -8
(i)348 10. ´ 5 (ii) 1215 10. ´ 7 10 9 -1 10 8
.
(iii)30001 10. ´ 8 (iii) 0.00000000621 = 621 = 6 21 ´100
348 10 11 10 11
Solution: (a) 348 10. ´ 5 = ´ 10 5 2
.
.
100 = 6 21 ´10 = 6 21
348 ´10 5 10 11 10 11 -2
= = 348 ´10 5 -2
.
10 2 = 6 21 = 6 21 10 -9
´
.
3
´
= 348 10 = 348000 10 9
1215 Example 18. The size of a Basil Plant cell is
(b) 1215 10. ´ 7 = ´ 10 7
1000 0.00001072 meters. Express it in scientific
1215 1215 ´10 7 notation.
7
= ´10 = 1072 1072 ´1000
.
10 3 10 3 Solution: 0.00001072 = =
=1215 10 7 -3 10 8 10 8
´
1072 ´10 3 1072
.
.
´
=1215 10 4 = =
10 8 10 8 -3
=12150000
-5
.
=1072 ´10 m
E xercise 2.3
1. Change the numbers into standard form and rewrite the statements.
(i) The distance from the Sun to Earth is 149,600,000,000 m.
(ii) The average radius of Sun is 695000 km.
(iii) The thickness of human hair is in the range of 0.005 to 0.001 cm.
(iv) The height of Mount Everest is 8848 m.
2. Write the following numbers in the standard form.
(i) 0.0000456 (ii) 0.000000529 (iii) 0.0000000085
(iv) 6020000000 (v) 35400000000 (vi) 0.000437 ´10 4
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Mathematics In Focus - 8