Our voyage in time now takes us to the land where tea, cricket and the Spice Girls are popular. That's correct, we're in England. Here we will meet perhaps the most revolutionary scientist in history, Sir Isaac Newton. In fact, here he is right now!

"Hello Mr. Newton sir, can I ask you a few questions please??"

"Ahh! What hideous kind of hat is that??"

"Um yah, I've been getting comments about it. Now, about those questions, would you please explain to me and my Internet friend here, your laws of motion you discussed in your book Principia?"

"Of course. Well my first law really isn't my law at all. I borrowed it from Galileo and got the credit, but it's okay since Galileo 'borrowed' ideas as well. Anyway, my first law is that An object will maintain its state of rest or constant speed in a straight line unless acted upon by an external unbalanced force. In other words, bodies want to stay in motion in a straight line at a constant speed, or at rest. This was referred to by Galileo as inertia. Thus, objects try to resist changes in motion when acted upon by an external unbalanced force. Thus, my first law attempts to set up or describe motion's tendencies. My second law relates this property to mathematics and explains why objects move. My second law states: When an external unbalanced force is applied to an object at rest or in constant speed in a straight line, the object accelerates in the direction of the unbalanced force. Furthermore, the acceleration of the object is directly proportional to the net forces acting on the object, and inversely proportional to the mass of the object being accelerated"

"Wow that's a mouthful Newton, perhaps you could simplify that a bit for me."

"No problem. Essentially when you apply forces (a push or a pull), the sum of all the forces is the direction in which the object accelerates. If the object is really heavy, it won't accelerate as fast; whereas if it's light, and the same force is applied, the object will have a greater acceleration. Mathematically this relationship is as follows:

(F is the sum of all the forces acting upon the object, m is the mass of the object, and a is the acceleration of the object.)

So you see, this relationship allows us to predict which way and with what acceleration an object will move when a certain specified net force is applied to an object."

"That is totally gnarly dude! Such a simple concept, yet it can be applied for many practical applications! Tell me more"

"Of course, but only if you refrain from using such awkward tenses of English like gnarly or dude. Anyway, my third law is perhaps the most recognized, but the most misunderstood. This law states that: When an object exerts a force on a second object, the second object will exert a force of equal magnitude, and opposite direction on the first object" This law is most commonly stated as 'for every action there exists an equal and opposite reaction.' The flaw in this version is that it doesn't say that the forces exerted are on different bodies. Thus, the forces do not simply cancel out as some may expect, rather they are transferred to the other object. My favorite example of this law is exhibited by cannon fire. When you fire the cannon, the cannon ball is pushed forward by an explosion in the cannon.

My law kicks in when the explosion happens. As the bullet is pushed forward by the gun, the bullet pushes back on the gun. This is seen by the jerk in the rifle when it is fired. So, the force the gun pushes on the bullet is equal to the force the bullet pushes back on the gun."

"Fascinating Newton! But I don't understand why when the gun is fired, the gun and man shooting don't get pushed back as fast as the bullet?"

"Good question. You see if you look back to my second law, force is inversely related to mass. Because the mass of the bullet is very small compared to the mass of the gun and man, they don't accelerate backwards as quickly. However, they do get the same force returned to them. The reason why this force doesn't kill the man is because most of the 'pain' is absorbed by the barrel of the rifle (gun)."

"Very neat, but I have one more question. Why is it that the man firing the gun doesn't slide backwards when he fires the gun?"

"An excellent question. You see when the man is pushed back by the bullet, he has a retarding force exerted upon him. Galileo first noted this force, which I call friction. This frictional force slows the shooter down very quickly, if he is exerting a lot of pressure on the ground, or if the ground is very rough. But you see, if the shooter were to fire his bullet standing on a friction-less surface, then he would be pushed back such that he would keep moving for ever."

"A very interesting discussion. Thank you for your time Newton."

"A pleasure, and perhaps next time we meet you could change your hat."

"Ha Ha"

There are three main laws of motion Newton described. Firstly:

1.)An object will maintain its state of rest or constant speed in a straight line unless acted upon by an external unbalanced force

2.) When an external unbalanced force is applied to an object at rest or in constant speed in a straight line, the object accelerates in the direction of the unbalanced force. Furthermore, the acceleration of the object is directly proportional to the net forces acting on the object, and inversely proportional to the mass of the object being accelerated (F=ma) "

3.) When an object exerts a force on a second object, the second object will exert a force of equal magnitude, and opposite direction on the first object

In addition to Newton's laws, he discussed the concept of friction. This is the same force described by Galileo as the retarding force. Although it was not exactly stated by Newton, the force of friction is related to the amount of pressure you apply at a point. Friction is not related to area. In general terms, friction is when two dissimilar surfaces interact with each other creating an opposing force. But, friction also occurs with objects that are very similar such as glass. If you put two sheets of glass on top of each other and try to move one of them, you will see that it is very difficult. This is as a result of molecular bonding that forms quickly when the two pieces of glass are put on top of each other. Thus the two pieces essentially bond to be become one piece. Since it is hard to break molecular bonds, the person who pushes the glass experiences difficulty - a resistance force - friction. Thus, friction is also noted to exist when you exert a force on an object that rests on a similar object.

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