Sir Isaac Newton: It's a Wonderful World of Motion
Most folks know who Isaac Newton is. However, how many of us can state his three laws of motion? Well, here is your chance to amaze your friends-at least, yourself-with a bit of knowledge. I, personally, can't stand physics, but it doesn't take a rocket scientist to understand the basics.
So, are you ready to get smart?
Okay! Enough said. Here we go...
According to Sir Isaac Newton's Principia,
1) "Every object continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it."
To understand this, imagine an incredibly large and obese fat man reclining upon a chair. He is next to a pool. The sun is glistening upon his skin. The perspiration swelters and sweats from his near naked body. In his own way, he is altogether lovely and picturesque, isn't he? At any rate, according to Newton's first law of motion, a fat man will remain at rest, and continue to remain at rest, until something along the lines of hunger (or, perhaps, the heat) acts upon him. The same thing goes if the fat man were to somehow manage to get himself up and put himself in motion. Unless something came along and caught his attention-take a meat sandwich, for instance-the fat man will continue on his merry way indefinitely. Well, in theory, anyway. Simple enough? Okay, next...
2) "The acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object."
This one is fairly basic. To illustrate, if we were to put an incredibly large and obese fat man on a skateboard, and push him along, his forward acceleration will be directly proportional to the net force we exert upon him. Without the skateboard, of course, there would be little to no movement. Notice, the wheels of the skateboard lesson the friction between the ground and the fat man. This is a key point. In any case, and according to Newton's second law, a fat man's acceleration is equal to the amount of acceleration applied to him. Ever wonder what would happen if we were to attach rockets to a fat man's back and attempted to shoot him toward the nearest star? I guess this would be our sun, but would he lose a few pounds along the way? Hmmm... This certainly requires a deeper understanding of physics. Still, it is interesting to think about. Oh, the wonders of science! And finally...
3) "Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first."
Every action deserves an equal reaction. The fat man eats a meat sandwich. The fat man widens. The trick here is working out who is acting upon what. Don't worry if you can't figure it out. For most gluttonous Americans, Newton's third law is a bit difficult to grasp. We'll just leave the answer to this one to the meat sandwich and the proportionally large fat man.
And, thus, ends my lesson on physics. It's all about knowledge, folks. It really is.
Hewitt, Paul G. Conceptual Physics (Tenth Edition). San Francisco: Pearson, 2006.