Levers for the Dummy Physics Student

Mechanical disadvantage in a lever system

Most of our nominees for the Antisocial Network's daily award are freelance writers who have sacrificed any credibility they might have had for a few pennies in reward; pretending to have knowledge of some facts or procedure for no other reason than to expand their bank accounts. Today's a little different. Not much, but a little: today's nominee got some of what he wrote correct, but he presented it so badly we couldn't help but wonder how he completed that journalism degree. Have a look at what Sciencing.com contributor Brock Cooper did to the topic, "Mechanical Disadvantages of a Lever System."

Cooper started off more or less correctly, defining a lever as one of the simple machines; although he hosed the count of simple machines with a missing comma:

"The lever is one of the fundamental simple machines of mechanics, along with the inclined plane, wheel and axle, screw wedge [bolding ours] and pulley..."

He also defined the three classes of levers, albeit clumsily:

"Type 1 is a rigid bar with the fulcrum centered like a seesaw. A Type 2 lever has the load before the fulcrum and the force applied in front of the load, such as a wheel barrel. The final type has the load at the end, with the fulcrum placed before the force, such as the human arm."

We assume that awkward verbiage such as "fulcrum placed before the force" and "load before the fulcrum" are an effort to avoid being nailed for plagiarism for using the word "between."

Next, Cooper wasted several dozen words by conflating "mechanical disadvantage" with "wear" and "precision," apparently thinking that "disadvantage" refers to problems of some sort. Ahhh, the inherent limitations of a liberal arts education...

Cooper finally got around to conveying some of the answer... well, sort of:

"The third type of lever has the disadvantage of reducing the force exerted on the system. The force is between the load and the fulcrum. While it does create a mechanical advantage, it reduces the overall force, leading to inefficiency in the system."

What Brock tried (and failed) to say is that the mechanical advantage of a Type III lever is always less than one, and therefore is a "disadvantage." In fact, any time the effort arm of a lever is shorter than the resistance arm, the lever has a mechanical disadvantage. Ergo, all three lever classes can have a mechanical disadvantage. Unfortunately, Cooper didn't know that, not to mention that what he did post is well-nigh unreadable. Now do you see why we named him the Dumbass of the Day? Sure you do!

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