Hover your mouse over the last frame for a little extra.
Tuesday, February 23, 2010
xkcd
Something most people don't know about me is that I love physics. I never took physics class, but during high school and part of college I would often spend my spare time reading a physics book I had bought. Yeah, I know, I'm a nerd. A friend showed me this website, xkcd.com, that hosts a bunch of web-comics made by a physicist. Here's a little example -
Hover your mouse over the last frame for a little extra.
Hover your mouse over the last frame for a little extra.
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2 comments:
Yo Jeffery
Nice expression: keep it up - you are improving in your freedom of writing,
peace, Bruce
Jeffery,
I was a college Physic Math major - did not graduate in that degree - but this i know:
Laws of motion
Newton's laws of motion are three physical laws that form the basis for classical mechanics, directly relating the forces acting on a body to the motion of the body. They were first compiled by Sir Isaac Newton in his work Philosophiæ Naturalis Principia Mathematica, first published on July 5, 1687.
Newton used them to explain and investigate the motion of many physical objects and systems.
For example, in the third volume of the text, Newton showed that these laws of motion, combined with his law of universal gravitation, explained Kepler's laws of planetary motion.
First law
There exists a set of inertial reference frames relative to which all particles with no net force acting on them will move without change in their velocity. This law is often simplified as "A body persists its state of rest or of uniform motion unless acted upon by an external unbalanced force." Newton's first law is often referred to as the law of inertia.
Second law
Observed from an inertial reference frame, the net force on a particle of constant mass is proportional to the time rate of change of its linear momentum: F = d(mv)/dt. When the mass is constant, this law is often stated as, "Force equals mass times acceleration (F = ma)": the net force on an object is equal to the mass of the object multiplied by its acceleration.
Third law
Whenever a particle A exerts a force on another particle B, B simultaneously exerts a force on A with the same magnitude in the opposite direction. The strong form of the law further postulates that these two forces act along the same line. This law is often simplified into the sentence, "To every action there is an equal and opposite reaction."
In the given interpretation mass, acceleration, momentum, and (most importantly) force are assumed to be externally defined quantities. This is the most common, but not the only interpretation: one can consider the laws to be a definition of these quantities. Notice that the second law only holds when the observation is made from an inertial reference frame, and since an inertial reference frame is defined by the first law, asking a proof of the first law from the second law is a logical fallacy. At speeds approaching the speed of light the effects of special relativity must be taken into account.
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