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Earth and other celestial bodies are an object of fascination for many .Over the period of more than a century, science has grown to discover the mysteries related to it and one of them is gravity. It is almost unbelievable how earth has the apt amount of force to hold everything and another important concept which is connected with it is acceleration. This article will give a brief description about both .
Gravity and Acceleration
Physics has always been a daunting subject for everyone who wishes to study science. Scientists like Newton, Einstein, Galileo have done phenomenal work in the field of Physics and with their discoveries, have made the life of scholars and students more accessible and put a stop to all the why’s and how’s.
Gravity
Gravity can be defined as an attractive force between any two objects. There’s a gravitational pull between every object on this earth that attracts them towards each other. Every single body has a centre where its whole mass is concentrated. This in physics is known as the ‘Centre of Mass.’
We often wondered as to why the planets in our solar system, the sun, the moon and all the celestial bodies are of a particular shape. Why are the planets in our solar system, the moon and the sun are all thought to be spherical?
- Why do some man-made satellites that encircle the planet, e.g., the earth take only 90 minutes?
- Why is the moon thought to take less time, i.e., 27 days, to encircle the earth?
- And why do some satellites that were sent to the universe fall back on the earth’s surface?
All of this is possible only because of gravity. That is why the study of gravitation was carried out by Newton to provide the answers for all these queries and many other questions related to the same concepts.
Gravity is studied under the class of forces known as ‘Gravitation.’
There are many types of interactions found in nature. Gravitation is among the four classes of interactions present in nature. The four types of interactive forces are:
- The gravitational force is found usually between planets and celestial bodies.
- The electromagnetic force that is found between the electromagnets.
- Strong nuclear forces are found in nature. These forces are also known as Hadronic forces
- The weak nuclear forces found in nature are interactive.
Acceleration due to gravity
When an object is dropped from a certain height above the distance from the ground, it begins to fall towards the planet earth. It happens because of gravity. The acceleration formed in the object’s body due to this gravity is known as acceleration due to gravity. It is called acceleration due to gravity because the body gets accelerated due to the presence of gravity.
- The symbol for the denotation of acceleration due to gravity is ‘g.’
- Its value is calculated to be 9.8m/second2.
Value for g concept and value of g meaning
Certain assumptions put forward the value for the g concept.
Suppose that the earth’s mass is taken as ‘M’, its radius is assumed to be ‘R’, then is a body whose mass is ‘m’, the force of attraction between the earth and that body kept close to the earth’s surface is:
F = G*M*m/R2
and
As per the second law put forward by Newton, the acceleration due to gravity is calculated by using the following formula:
g = F/M = GM/R2
The following formula says that the acceleration due to gravity is free from the mass of the object’s body.
This formula helps us to understand the free fall of two bodies. If the two bodies fall freely, having different masses, they will reach the earth’s surface simultaneously. This means that the free-falling of the bodies is independent of their masses.
Factors on which the value of ‘g’ depends
The value of ‘g’ changes. It is variable for a place to place on the earth’s surface. Different places on the earth’s surface have different values of ‘g’. As we go above the earth’s surface or below its surface, variation in the value of g is observed.
Therefore, the value of ‘g’ depends on the following factors:
- The shape of the earth
The earth’s shape is assumed to be a sphere, but it is not a perfect sphere. It was observed that it is somewhat flat at the two poles of the planet, i.e., the North Pole and the South Pole. The equatorial radius is calculated to be approximately 21km more than the radius of the two poles. Hence, it is observed that the value of ‘g’ is found to be minimum at the equator and maximum at the two poles.
- Height above the Surface of The Earth
The height above the earth’s surface also affects the value of acceleration due to gravity. It was observed that as we go above the earth’s surface, the value of ‘g’ goes on decreasing.
- Depth below the Surface of the Earth
The acceleration value due to gravity was also observed at a depth below the earth’s surface. It was found that its value went on decreasing.
- At the centre
It was observed that the acceleration due to gravity was at the earth’s centre.
Conclusion
Gravity holds the objects together. Because of gravity, only the earth and other celestial bodies can revolve around the sun. Gravity finds its importance in astrophysics that focuses on understanding the universe better.
