The Acceleration of Gravity for Physics Dummies

Although our scientifically-literate staffers are constantly irked by the half-baked copy-reword-paste jobs performed by journalism and creative writers "explaining" science, scientific illiteracy coming from people who claim to be scientists is even more irritating. That's why we're pleased to be able to present today's DotD award to an eHow.com contributor who claims to be studying physics. Were that the case, though, Lee Johnson would likely have done a better job of describing "Science Project: The Effect of Mass on the Distance a Ball Travels"¹ for Sciencing.com.

Johnson described an experiment involving a ramp and a number of balls of different masses. Besides the fact that Lee merely changed "toy car with low-friction wheels" in the experiment he cribbed to "ball," he botched the experiment by failing to copy the use of a track in the original experiment. Johnson's model would allow the balls to wander aimlessly about the floor at the foot of the ramp. Idiot.

What's worse for our geeks, however, was witnessing someone who claimed to be a physics student explain the action of gravity on the balls thus:

"Gravity pulls the balls down the ramp, and the force of gravity is bigger on larger-mass objects."

Uhhhh, no, Lee, that claim's only correct if one has extremely sensitive measuring equipment. The force of gravity is dependent on 1) the distance between the center of the earth and the center of the ball, and 2) the product of their masses. Given that the mass of the earth is very likely 24 to 25 orders of magnitude larger than the mass of the experimental balls, it's unlikely that the "force of gravity" is measurably larger on more massive balls resting on Earth's surface.

What Johnson should have been talking about is Newton's second law (the yutz even referenced it!) and the acceleration of the balls due to their differing masses according to the equation F = ma. Had he mentioned that, he could have then explained that the velocity of the balls when they reach the base of the base of the ramp varies with their masses, and that the distance traveled from that point is a function of that velocity.

But he didn't. Instead, Johnson told everyone that "good experimental design is important." Well, Lee, that's definitely true; but understanding the scientific principles under study is just as important. This description introduces an error, because it skips a critically important step in the students' understanding of the physics of the experiment. We call that a Dumbass of the Day error...

¹ Interestingly enough, this is Lee doing a rewrite of a piece of rubbish written by multiple DotD winner "Serm Murmson," who – believe it or not – did an even worse job. The original can be found using the wayback machine at archive.org; just look for the URL    sciencing.com/science-project-effect-mass-distance-ball-travels-2550.html

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