As a kid we all were restless. We wanted to play! We wanted to run! We wanted to swim! We wanted to fly! But our teachers and parents made us sit in a place and study. They thought making us sit in the study corner, we would be still. But the million dollar question is Are we actually still? Can anything be static in this universe?
The answer is NO! It is just not possible. Nothing in this universe is at absolute rest. The object is said to be at rest with respect to a frame of reference. If you are sitting on a chair. You are static with respect to the room inside which you are sitting. But when you are observed from the moon, you are moving with the speed of 1600km/hr considering Earth’s rotation alone. Thus, the same idea can be extended to everything at every point on this universe.
If everything is moving on this universe, then what makes an object to stop? The answer is, an object is stopped when a resisting force acts on it opposing its motion. Scientists named it Frictional force. Well, how does it stop the moving object? Assume that, you have rolled a ball on the floor. Here to initiate the motion, you have applied a certain amount of force(to overcome static friction) and ball rolls in that direction.
The ball initially rolls with higher speed and gradually speed decreases. After an interval of time, it comes to rest or it stops. This is due to the atoms on the top of the floor which will resist the motion, as a result, friction arises which in turn stops the ball. The friction that stops the moving object is called kinetic friction.
If the ball stops after an interval of time, why not Earth or Moon or any celestial bodies? The simple answer is why will it stop? when there is nothing to stop it! Yes, you have read it right. Friction is applicable only when there is an environment(when the object is in contact with air, liquid or solid). The open space is out of the vacuum. The vacuum does not possess any frictional force. So due to big bang whatever set to motion, continues to be in the state of motion forever.
Although celestial objects are surrounded by vacuum, they do comprise of the local atmosphere. For example, our own Sun has his atmosphere, which is full of magnetic fields and other radiations. Our mother earth also has her own atmosphere. Which readily supports all electric and magnetic phenomenons, like Propagation of EM waves, the formation of Electric dipole, inhalation, and creation, etc.
Thus, you have got a brief idea about this dynamic universe. Wasn’t it interesting!
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