Gravity force | Gravitational Force explained | 2018

Gravity force - While defining gravity force, the question arises that What gravity actually is? Why is gravitational force an unsolved and exciting question? Why do we still do not understand the reason why the gravity force is so different among all the four fundamental forces of nature? Why this topic is so important? And why Sir Issac Newton and Albert Einstein became so famous for this?

Gravitational Force explained in detail

To know and understand this phemomenon, let’s go back in time. It all started way back in the 17^th century on the year 1661 when Newton was at the age of 18. He left his home at this age and took admission in The Cambridge University. Later in the year 1665 there was an epidemic of Plague over London which had a very drastic effect on London and along with this The Cambridge University was also shut down and hence Newton had to return home. And because of this, Newton now had all the time in the world to carry on his research.

Know about spacetime and its peculiarity

Near his house there was a garden full of apple trees where he used to spend some time sitting under a tree and tried to understand the secrets of the universe.

Then one day that famous incident occurred which gave birth to modern day physics. An apple fell near him. Looking at the apple Newton thought why did the apple fall down and why not anywhere else. So he started his research and finally said that the force which makes the apple fall on the ground is gravity and also he said that gravity doesnot only work on earth but also in the whole universe. Then he explained this in a peculiar way.

He assumed that we put a canon ball machine on top of a hill. Now if we fire the canon ball then according to Newton’s First law of motion the ball must travel in a straight line forever untill and unless an external force is applied to it. But due to gravity, the canon ball falls back on the earth. Now if we increase the speed of the canon ball then the ball travels a bit more further distance but still falls back on earth. Now if we keep increasing the speed of the ball then a time would occur when the ball would go into an orbit and revolve around the earth. Now using this theory, he explained the revolution of moon around the earth and also with this theory, he explained the revolution of other planets in the universe.

For this theory he gave an equation which is the gravitational force is directly proportional to the product of the masses of the bodies which is divided by the square of the distance between them.In simple language, this means that any two bodies however small or however large they be or whatever their masses be but they attract each other. But this force is very small, hence to solve this Newton added an universal constant whose value is also very small. He couldn’t calculate the value so he gave it a name as ‘G’. So his equation now looked like- ‘F=GMm/R2’.

Later a scientist, Henry Cavendish experimentally evaluated the value of G.

After this Newton tried to understand Kepler’s law finding gravitational acceleration of any planet etc.

Mathematically it is shown that According to Newton’s Second Law of motion, F = ma which means the net force equals the mass of the object multiplied by the amount of acceleration. Also we know, a = GM/R2.

Now in gravitational field, the acceleration is equal to the gravitational acceleration ‘g’.

So we get, g = GM/R2.

These equations are so accurate that NASA and ISRO still uses these equations for any space mission.

Now when Newton observed the falling of apple more distinctly, he found something more strange. Before that Aristotle gave a theory that if we through two bodies of different masses from a certain height then the one with the more mass will fall fast but it was proven wrong by Galileo with his experiments. He said that even if there is a vast difference between the two masses but still theyt will fall with the same velocity as the gravitational acceleration of any planet is same for all objects.

So if we want to measure the average speed of any object, say an apple then we would simply have to divide the distance travelled to the time required. But Newton wanted to find the speed of an apple at any instant time which was not possible but the total average velocity. So for this he needed to find the average velocity for a very small time interval which will tend to zero but not equal to zero. Hence for this reason Newton found out a new branch of mathematics called Calculus and this Calculus is now the backbone of Modern science.

Using this Calculus he proved the inverse square law of Gravity. Now according to this law, if the apple is twice as far from the centre of the earth then the force due to gravity will be four times less.

But when Newton Published his paper then questions arised from everywhere that How does Gravity act on everything but he literally didnot had any answer for this. He said that it is a mysterious force of nature which acts by itself. But Gravity is more mysterious then Sir Isaac Newton could think about.

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All about Gravity Explained