# Newtons First LawThe Law of Inertia

Newtons first law the law of inertia basically states that an object at rest will stay at rest and a moving object will keep moving at a constant speed in the same direction unless unbalanced forces act upon the objects.

This means that an object like a ball won’t just suddenly fly through the air on its own accord without being thrown or acted upon otherwise. This seems quite logical really as long as nothing makes it move it won’t move.

For an object to be at rest the forces on it if any have to be balanced. For a force to be balanced it has to be countered by a force of the same magnitude in the opposite direction. For example if a human were to stand upright on the surface of the earth, gravity would be exerting force on that person. That person would not accelerate downwards since the surface of the earth would push back with the same amount of force. It may seem weird to think of a wall pushing back, but
Newton’s third law means that since the wall is being pushed it has to
push back.

Here on earth every object comes to a halt due to three main forces air friction, drag and gravity. Even the most powerful bullet will drop from the sky due to gravity and slow down considerably due to air friction. This makes easy to assume that objects will always return
to their natural state which is at rest. This was believed by Aristotle and many others also believed his theory from 500 BC to 1600 AD. Though, this is not true. Objects want keep doing what they are doing no matter whether they are at rest or in motion. Out in the vacuum of
space there is no apparent drag and objects can keep moving at a constant speed for an indefinite amount of time provided there are no obstacles.

The most exciting phrase to hear in science, the one that heralds the most discoveries, is not "Eureka!" (I found it!) but "That's funny..."
-- Isaac Asimov --

Newtons first law is actually subconsciously used by many people. For example getting out the last bit of ketchup out of the bottle many people would accelerate the bottle and then letting the
inertia of the ketchup carry it out of the bottle. Of course it also helps that ketchup is a shear thinning non-Newtonian fluid.

Newtons first law is applied by the motorists all around the world. When driving a car we do not expect it to stop instantly just because we take our foot off the pedal. We use the brakes to stop the car because it will want to keep moving unless an unbalanced force stops it in this case the brakes and not a wall.

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