6. INTRODUCTION
According to Newton’s Law of
Gravitation,every objects in the world attracts
each other.And this force of attraction is directly
proportional to the product of their masses and
inversely proportional to the square of the
distance between them.
When a body is in free fall,this force is
used to give acceleration to the body.Let us now
Discuss about this acceleration.
7. sssssss
Accleration due to gravity
It is defined as the acceleration of a freely falling
body due the Gravitational force of attraction
exerted by the earth.It is denoted by the letter ‘g’.
Accorging to Newton’s second law of motion,
Therefore,
8. centre of mass of the object,r.
2. Mass of the planet,M.
M will be a constant forr each planet.And G is
the universal gravitational constant.The acceleration
due to gravity is independent of the mass of the freely
falling body,m.
FACTORS AFFECTING ‘g’
The factors affecting g are,
1. Distannce from the centre of the planet to the
9.
10. ‘’
Dependence of ‘g’ on R
The diatance,R from the centre of earth to
the equator,is large compared to that to the poles.The
value of g is found to be , g = 9.83 m/s^2 at poles and
9.79 m/s^2 at equator.The average value of these two is
taken as the standard value of g.
i.e,
g = 9.8 m/s^2.
11. Graphical representation of variation of g
from the centre of earth
The value of g varies g varies inversely from the earths centre .
12. The value og g at different places
from earth’s centre
The value of g at different places is given on the table.
Location
Distance from Earth's center
(m)
Value of g
(m/s2)
Earth's surface 6.38 x 106 m 9.8
1000 km above surface 7.38 x 106 m 7.33
2000 km above surface 8.38 x 106 m 5.68
3000 km above surface 9.38 x 106 m 4.53
4000 km above surface 1.04 x 107 m 3.70
5000 km above surface 1.14 x 107 m 3.08
6000 km above surface 1.24 x 107 m 2.60
7000 km above surface 1.34 x 107 m 2.23
8000 km above surface 1.44 x 107 m 1.93
9000 km above surface 1.54 x 107 m 1.69
10000 km above surface 1.64 x 107 m 1.49
50000 km above surface 5.64 x 107 m 0.13
13. Value of g at the centre of earth
When the object is placed at the centre is earth,the
distance of the object from the centre of earth,r is
zero.Therefore the value of g is also zero.
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14. Variation of g at different planets
The value of M and R are different for different planets.
Hence the value of g is varies from planet to planet.
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15. What is the value of g at different
planets
The value of g at different planets are given
below.
Planet Radius (m) Mass (kg) g (m/s2)
Mercury 2.43 x 106 3.2 x 1023 3.61
Venus 6.073 x 106 4.88 x1024 8.83
Mars 3.38 x 106 6.42 x 1023 3.75
Jupiter 6.98 x 107 1.901 x 1027 26.0
Saturn 5.82 x 107 5.68 x 1026 11.2
Uranus 2.35 x 107 8.68 x 1025 10.5
16. Do you know?
The height of Eskimos at the poles
Is small compared to others !!! ...
17. A picture is worth a thousand words
A complex idea can be
conveyed with just a single still
image, namely making it
possible to absorb large
amounts of data quickly.