Newton's Laws for and by Dummies

Impact of a  bullet, Newton's second law

There are lots of reasons why the television show "The Big Bang Theory" is wildly popular. It could be because Penny is hot (though not as hot as she was when the show premiered). It could be because it's amusing to make fun of Sheldon's obvious OCD + Asperger's + other tics and twitches. Here at the Antisocial Network, however, we think it's because it's supposedly funny to mock things we don't understand, and the four guys are all scientists – three of them different flavors of physicist – and most people don't "get" physics. No, they don't get it at all, and eHow.com's Neal Litherland is the perfect example. Just look at how this dummy screwed up "Newton's Laws of Motion Made Easy" at Sciencing.com.

Anyone who's had a classical physics class, high school or college (and maybe even AP science in junior high) has heard of Newton's three laws of motion. Litherland's degree in "criminal justice," apparently, did not include such information. As a result he had to reword examples he found somewhere else, along the way changing some of the wording to make it "prettier." Oops: you can't do that with Newton. After all, Neal, you said it yourself:

"Sir Isaac Newton is considered by many to be the father of modern physics."

That's a misstatement, though; modern physics, e.g., quantum physics is, to be polite, non-Newtonian. On the other hand, classical physicists (and high-school students) still deal daily with Newton's three laws. Most of them, however, get it right. Litherland didn't when he wrote bull like

"The second law is, 'The relationship between an object's mass M and acceleration A, and the applied force F is F=MA. Acceleration and force are vectors, and in this case the direction of the force vector is the same as the direction of the acceleration vector.'" That's not quite what Newton's second law says: it actually says that the acceleration of an object is directly proportional to the net force applied and indirectly proportional to the object's mass (the formula in Newton's Principia is originally a = F/m). Although it's a quibble, Litherland shouldn't be capitalizing those variables a and m, either... Quibbles aside, it's when Neal got to his alleged examples that he truly screwed the pooch. Take a look at his example for Newton's second law:

"...a bullet is stationary until the trigger is pulled and the gunpowder explodes. The power of the explosion is the acceleration (A), and the weight of the bullet is the mass (M). The force of the bullet (F) is measured as the mass times its acceleration, and can be said to be the impact that the bullet will strike with."

That's utter bull! the bullet's acceleration is not the "power of the explosion"! The exploding gunpowder is an accelerant, not an acceleration. Acceleration is the rate of change of velocity; something entirely different from an explosion! Furthermore, the force of a bullet's impact is a result of its deceleration (negative acceleration) when it strikes its target. While the bullet is in motion it has no "force"; only potential energy.

Litherland further munged up his explanation of Newton's third law ("For every action, there is an equal and opposite reaction") with a simplistic and incomplete example:

"The easiest way to see [Newton's third] law in action is to step off of a boat. The force that the person uses to push himself forward ends up pushing the boat backward in an equal, yet opposite manner."

Besides its clumsy construction, this example fails to mention that the two forces will be equal, which means that the product of the person's mass and forward acceleration is perfectly balanced by the product of the boat's mass and rearward acceleration; a critical observation Litherland clearly failed to comprehend.

This is just another example, one of many such at eHow, of a scientific illiterate attempting to describe scientific principles in "plain language." We think readers would be better served to learn how to understand that "science-y" stuff by learning about science (instead of for example, about celebrities). If they can't, there are people out there who do understand the science and can also couch its principles in plain language. Fortunately, Bill Nye, Neil deGrasse Tyson and their colleagues will never qualify for Dumbass of the Day – something you can't say of Litherland...

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