h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Newton's three laws of motion are a continuing myth perputated by a scientific community obsessed with 'nice' numbers. Specifically, three being a nicer number than two.

If you look closely at Newton's second law you will see that it says everything the first law does and a little more.

The second law says that an overall force in any direction will cause an acceleration in that direction, proportional to the force. Newton's first law says that if there is no overall force acting on an object then its velocity will not change.

So the first law says no force means no acceleration and the second law says some force means some acceleration.

If Newton was not fixated by the number three he could have rolled laws one and two into one and made law three (which I have no arguments with) into law number two.

In my understanding, the first law emphasises the fact that a body needs a force acting upon it to change its velocity. The second law, on the other hand, is concentrating on the proportional relationship. While they are similar, they are different enough to warrant classification as two separate rules (in my opinion anyway).