Children have always wondered about why humans don’t fly, why a stone
thrown upwards in the sky returns back to ground, why do we fall if we jump
from a height, why does an aircraft require so much push to take off? What
makes everything fall on the ground?
To the layman, a standard explanation of gravity is the reason why
objects fall. Discovered by Isaac Newton, gravity in its basic principles can
be defined as the relationship between any two objects in the universe based on
their masses and relative distance. In other words, when the mass of the
objects is high and the distance between them is less, the gravitational pull
or the attraction between the two becomes stronger. E.g. the mass of the earth
is high and the mass of the humans is also high, but since the earth has a
greater mass (thus greater gravitational pull) we are attracted towards it, but
to move away from the gravitational pull of the earth we would require a very
strong force.
It is the gravity which positions our planets, moon, and sun and
clumps the stars together into galaxies. Gravity plays a very important role in
making the universe. We are not aware of the Sun’s gravitational pull because
it is so distant from us, but it is the sun’s gravitation that positions the
earth where it is. The gravitational force of the moon is known to cause tidal
waves in the oceans. The concept of Gravity is complex and hence, it needs to
be understood with experiments https://youtu.be/p_o4aY7xkXg
Experiments
explaining Gravity:
Several experiments have been
conducted on the topic of gravity which can be understood from the concern
videos. They include
Acceleration due
to gravity (http://study.com/academy/lesson/the-acceleration-of-gravity-definition-formula.html),
Earth’s
Attraction
Through researches it has been observed that the earth has an
invisible magnetic field which pulls us and other objects towards its center,
this magnetic field is called gravity. When any object reaches beyond the
magnetic pull of the earth, the gravity starts weakening and thus the object
floats, however, the gravitational attraction does not end.
Gravitational pull of two small objects in a spacecraft would be
overpowered by other forces like the circulation of air available etc. In the
space the shuttles orbit the gravitational pull of the earth. It has been
discovered that the earth’s gravitational pull in a space shuttle will be 11%
less than that on its surface.
Using a simple
pendulum to measure Gravity
When we swing a
pendulum sideways from its resting position it faces force due to gravity which accelerates it back towards
its resting position. When we swing it sideways and release it the force of our
push combines with its mass (weight) and creates oscillation around the resting
position in back and forth movements. The time it takes to swing left to right
be called period (T) and it is dependent upon the length of the pendulum (L)
(also called the radius of oscillation) and the force and width with which it
was swung. The formula used is:
To understand
more about the concept you can go through the video https://www.youtube.com/watch?v=DUOlEyPH9Fo
The Universal Gravitation: Sun, Earth, Moon and
the Planets
Universe has
around 100 billion galaxies, each galaxy has almost 100 billion stars, among
which one is ‘The Sun’. The sun moves around our galaxy- ‘the Milky Way’. Our
solar system consists of the Sun, the nine planets, the planetary moons, comets
and asteroids. Both Sun and Earth move around a common center of gravity, but
since the sun is huge and has more mass than earth its gravitational field
extends to that of the earth and as a result the earth rotates around the sun.
This is the reason why the sun always rises from the east, and the sun revolves
in 12 constellations which we refer as zodiacs.
The earth and our
moon are considered to be a binary system with the same source of gravitational
pull. Though the gravitational pull of sun is greater than the earth, but since
the moon is closer to the earth and earth’s gravitational impact is greater on
the moon than that of the sun, the moon revolves around the earth - https://www.youtube.com/watch?v=W47Wa7onrIQ
Micro Gravity-
weightlessness
The feeling of weightlessness on performing various acts like jumping,
while in elevator, being at the top of a giant wheel are all related to this
principle. The weight of an individual is measured on a weighing scale where
the weight of the body is on the scale and the scale exerts an equal force on
the body and that is the calculated weight, but when an individual pushes
against the gravitational force of the earth the weight is recorded as zero.
This causes a feeling of floating while you are being pulled by the
gravitational force. So, how much do you weigh depends upon your relative
position and force against gravity. In space the individual weighs 11 kgs less
than his/her earthly weight.
Throwing a ball
into space
The gravitational pull of the earth is very strong, which requires the
spacecrafts to exert pressure opposite to the gravitational field to enter
space. The below diagram shows that if a ball is thrown at a 40,320 km/hr
(24,436 mph) only then it will reach point L1 where the gravitational field of
the Moon would work, causing the ball to come up at a greater speed unless it
hits the land on the moon. This is practically impossible to do!
Let us recollect the ways in which gravity is affecting our life and
analyze how important it is for the universal existence. What would happen if
the gravitational field was suddenly suspended? Run your imagination on how the
world would be then!!
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