Do We truly Understand Newton's Laws Of Motion?
Most of us know what Newton's three laws of motion states. But most of us do not truly understand what it truly means.
I wrote a physics exam about two weeks ago. This Sunday one of my country’s national newspapers wrote an article about that physics paper and criticized it for being scientifically incorrect and impossible to calculate. I faced problems that I thought was impossible to calculate. My first thought was that I did not study hard enough, because I could not do it. I asked my friends directly after the test if they also found some of the problems strange but only one of my friends agreed with me. But all of that 'funny questions was"mentioned in the news article for being impossible to correctly calculate. This made me realize that most of us know Newton's laws of motion by hart , but some of us do not truly understand Newton's laws of motion. This post will tackle Newton's laws of motion misconceptions and explain what it really means.
Newton's first law
The formal definition of newton's first law is : An object will stay in rest or move at a constant velocity , unless an unbalanced force is acted upon it. Usually we tend to forget the "move at a constant velocity” part and focus on the "stay in rest" part. This is because we live on Earth in an air filled environment which is good at creating friction when moving. We also feel a huge effect of earth’s gravitational pull. An object will always slow down in rest with all these forces acting upon an object! You can test this by spinning a coin or by throwing or rolling a ball on earth under our "normal"conditions. But if you were to float in the vacuum of space and throw or push the ball then it would move at a constant velocity in the direction the force acted upon it… forever…. Or until it crashes into another space object or fall into another planet or star! A ball would roll forever if we were to roll the ball on an air and floor friction free environment according to Newton’s first law of motion. This is really trippy if you think about it in terms of mathematics, an object moving at a constant velocity, lets say 2 m.s^-1, have a resultant force equal to zero!
Newton’s second Law
An object will accelerate if an unbalanced force is acting upon the object. This acceleration will be in the direction of the resultant force and is with this force. This means that an object will accelerate faster when you keep on increasing the force on an object. We usually tend to think that an object will start to move at a constant velocity when applying force to an object. We think this because of friction. A box only moves and does not seem to accelerate when you push a heavy box on the floor. But we can see that it is true by climbing in the car and stepping on the gas pedal. The more force the engine applies the more the car accelerates! Just something interesting, we can write Newton’s third law in the following equation F = m*a where f is the force, m is the mass and a is the acceleration. If we make the force acted upon an object = 0 then the acceleration must be 0 because an object's mass stays constant thus mathematically showing the third law again! An object moves at a constant velocity when the acceleration of the object is equal to zero.
Newton’s third law
“For every action is an equal and opposite reaction”. This is probably the most famous law of motion. this means that if one object A acts a force out on another object B then object B will act the same size force in the opposite direction on object A. Here is a diagram to visually show this:
The same happens when objects attract each other with gravity. I pull the earth with the same force towards me as the force that the earth pulls me towards it. This is trippy to think! The same with the moon. The moon pulls the earth with the same force as the earth pulling the moon! Here is why:
Imagine an object with identical mass like this diagram below. It would pull each other with the same gravitational force like this!
Image Credit: my own work
Now imagine that one of these objects turns two times heavier like in the diagram below. The lighter object B gets pulled by the Heavier Object A "old mass" and by the "new mass". The same with the heavier object A. Its "old mass" still gets pulled by the lighter object and so does its "new mass" as well! Look at the diagram to understand better:
Image Credit: my own work
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I found this post when searching for newton theories. And it was very useful for me to understand.
Thank you for posting. Issac Newton, one of the best. Cheers.
Very true! Can you imagine that someone back in those "dark" days made these observations, even without knowing what space is like. He is truly one of the best!
"This is an ELECTRIC universe of motion, not a Newtonian gravitational universe. Nor is the universe an objective material universe. Objectivity is only one single moment in the life of the entire cycle. That cycle is comprised of many such moments some of which are sensed as density and materialistic while others are beyond sensing !" - Dr. Walter Russell
If you want to replace a widely admitted theory by another one, the new theory should explain at least all observations and facts that the former theory explains. This is not the case of the electric universe. Therefore, in the meantime...
Great job with this post, really enjoyable to read! A nice basic physics lesson.