From Aristotle to Galileo to Newton to Einstein to Oppenheimer to Hawking to Thorne to DeGrasse Tyson. This world has seen a lot of great physicists, I know I missed many but I was going Generation wise. What was the founding stone for physics? Well I don’t know, maybe people were just fascinated by looking at the stars and noticing how things fall down and how things roll down, they were fascinated just like us. Newton discovered gravity, one of the most significant inventions in the whole of physics, more significant than Einstein’s actually. His laws of motion were a great revolution in physics too. These laws were the foundation of classical physics which you all study today. Taking account from discoveries by Aristotle and Galileo, he truly made 3 laws which describe half of physics. Today, we are going to talk about them. I am excited, let’s start this!
Just a little context, Newton’s 3 statements describe relations between forces acting on a body. Newton said that everyone has gravitational force as described in my earlier blog. He believes that 2 bodies having mass attract each other (I have talked about all of this in my earlier blog).
First Law of Motion (The law of Inertia)
Newton’s first law of motion states the following:- “An object does not change it’s state of motion unless acted upon by a force”. This basically states that an object does not change it’s motion unless you apply force on it. A common example is that when you are standing, you won’t move until someone pushes you. Newton believes that there is no difference between uniform motion and state of rest. An object cannot move until you apply force on it. When you do apply force, the object accelerates. The acceleration of the object depends upon how much force you applied and how much force is being applied on the object by the forces of nature such as electromagnetic and gravitational forces. Thus, I have already told you that,
Acceleration= Gravitational Mass by Inertial Mass x( Intensity of the Gravitational Field)
The mass depends because if you are too big, your acceleration will be less. Hence, the law of Inertia. Intensity of the gravitational field also matters because the more the force acted upon by the gravitational field, the less the acceleration. But in Newtonian physics, which is Acceleration = force by mass. Acceleration is equal to forces acting upon the object and it’s mass, a simplified form of Einstein’s acceleration equation. Friction is also a thing, please don’t forget that. Because the great Newton says, When you are moving at a constant speed, what stops you? Friction! Roll a pen (Please apply reasonable force depending on the table and the pen), and it will stop after rolling for some time (as in 2-3 seconds or maybe less) because friction is acting on it. That my friends was the first law.
Second Law of Motion
Newton’s second law of motion states the following:-“The force of an object is equal to it’s mass times it’s acceleration”. F=ma which is Force is equal to mass into acceleration. A little fun fact that in physics work is done only when you apply force and the object accelerates. For example, if you push a wall for let’s say 8.50 minutes. Rounding it off be 9 minutes. You think you did a lot of work and you are also tired, right? Well, according to PHYSICS! You didn’t do any work because the wall didn’t move. The force you apply solely depends on the object’s mass and acceleration. The more the mass, the less the acceleration. The less the mass, the higher the acceleration. But then again the amount of force applied also matters for the acceleration, hence F=ma. That my friends was the Second Law of Motion and now you know that both the first and second laws are interconnected.
Third Law of Motion (The law of action and reaction)
Newton’s third law of motion states the following:-“When 2 objects interact, they apply forces to each other of equal magnitude and opposite direction”. I have already given the same example in my previous blog but I will use it again (after all physics is interconnected). When you put a book on the table, the book exerts a downward force on the table, now the same way the table exerts an upward force on the book to hold it and to balance out the forces between them. I told in my previous blog that the force the table uses is electromagnetic force coming from the atoms and molecules of the book and the table coming in contact with each other and exerting forces upon them. The forces between these 2 were in opposite direction (upward and downward) and had the same magnitude so they could balance out each of their forces and cancel them out, so the table can hold the book. So much happens when you put a book on a table and you don’t even notice it (maybe notice it next time, oh wait, you can’t!). And that is why I like physics, studying about the laws of nature. That my friends was the third law of motion. This was the easiest one to understand, only took 1 example. I think the first law was the hardest.
And that's all she wrote! Newton’s Laws of Motion described. This one is for physics haters “Only if Newton didn’t exist, well then there had been another one”.
By
Deeparsh Bhanot
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