It was 1600s, when an apple fell from a tree on the head of an English physicist and Mathematician, Sir Issac Newton, at least that’s what the legends tell. It wasn’t anything new, yet it got him thinking. Why?
Why does the apple fall? Also, Why doesn’t it hold it’s position? If the apple falls, does the moon also fall? These were the simple questions which led to the discovery of gravitational force!
“Theory of Universal Gravitation” the reason why we should solve so many numerical problems in physics class nowadays.
Gravity and gravitational force, they’re two different things!
Gravity is the resultant force with which an object is attracted towards a heavenly body (especially Earth).
While gravitational force is the force by which various objects in the universe are attracted towards each other. Gravitational force is directly proportional to the product of the masses of the bodies, and is inversely proportional to the distance between the centers of the bodies squared.
F = Gravitational force
G = Universal Gravitational Constant
M1 = Mass of one of the bodies
M2 = Mass of the other body
r = Distance between the centers of the bodies
How does Gravity work?
Mass bends space time continuum. When space time continuum is bent, it forms a valley like structure (slope) around that body, and hence all the other lighter bodies nearby are attracted or fall towards it.
Here, in figure a, space time isn’t bend as there is no mass to bend it. Whereas, in figure b, there is a body which has certain mass and hence, it bends the space time. This causes gravitation, and hence, bodies are attracted.
Now, your curiosity may question, “If that’s the case then, why doesn’t the Earth fall on the Sun?”
Well, my friend, the Earth goes around the sun in its elliptical orbit, and it is always in a state of free-fall under the action of gravity of the Sun, but there’s the force of inertia too, due to which it remains in its orbit and goes around the Sun rather than falling on it. In space there’s no air resistance due to which the inertia remains constant causing the Earth to go round the Sun in its orbit.
For further explanation, watch the video: