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SREE NARAYANA TRAINING COLLEGE

SREEKANDESWARAM, POOCHACKAL

B.Ed 2014-15KERALA UNIVERSITY

SUBMITTED BY: NAYANA.K.V PHYSICAL SCIENCE REG NO:18214383015

SUBMITTED TO : Mrs.LINIMOL.K.S FACULTY OF PHYSICAL SCIENCE SNTC,SREEKANDESWARAM

ACCELERATION DUE TO GRAVITY

INTRODUCTION

According to Newton’s Law of Gravitation,every objects in the world attracts each other.And this force of attraction is directlyproportional to the product of their masses andinversely 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 nowDiscuss about this acceleration.

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Accleration due to gravity

It is defined as the acceleration of a freely fallingbody due the Gravitational force of attractionexerted by the earth.It is denoted by the letter ‘g’.

Accorging to Newton’s second law of motion,

Therefore,

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

‘’

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.

Graphical representation of variation of g from the centre of earthThe value of g varies g varies inversely from the earths centre .

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

Value of g at the centre of earthWhen 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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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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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

Do you know?

The height of Eskimos at the polesIs small compared to others !!! ...It is due to the strong gravitational force of attraction at the poles.

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