Saturday 14 November 2015

Newton's Third Law and the mess that people have created.

I, being a student and teacher of Physics, keep studying everything over and over again. And this habit of mine though seems stupid to many has actually given me rich rewards by giving me deeper insights into many a laws and theories of Physics.


It so happened that a couple of days back I was studying Newton's laws again just following my habit. And there I came to a rather bizzare conclusion. The books and authors who have written the definition of Newton's third law have got it all wrong or atleast translated it wrongly and the third law doesn't make sense.


To make my point let me tell you how it all fared.


I simply out of curiosity went on to look at the original way in which Newton had written the laws in LATIN.

Here is the original words of Newton Third law.


 Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi.

 
 Now I pasted it in Google Translate and this is what I got.


To every action there is always opposed an equal reaction: or the mutual actions of two bodies upon each other are always equal, and directed to contrary parts .
This kinda rattled me. What we study and what I have been studying and teaching all my life is something like this.

To every action there is an equal and opposite reaction. Now for the first time in my life it didn't make sense. I mean the above statement.


What sense does it mean, " ..... equal and opposite reaction..." .

 Its a meaningless statement. Someone made a historical mistake of trying to shorten the law and ended up making it meaningless.

Let us analyze the two horrendous mistakes.

1.  There is absolutely no mention of the direction. It is left to the assumption of the reader the opposite means direction is opposite.

2. It is also left to the imagination of the reader that equal means equal in magnitude and that equal doesn't mean same direction.
So a beautifully crafted statement by Sir Issac Newton was horrendously translated and then shortened into something that is meaningless and grossly wrong.

So here is what Newton tried to convey which I feel should replace the prevalent definition.

To every action there is a reaction; which is equal in magnitude and opposite in direction, and takes place on two different bodies.
What do you say???