The Types of Pulleys for Fifth-Grade Dummies

Pulley Types

Remember the TV show "Are You Smarter than a 5th Grader"? We're sure it's still on, somewhere... the fascinating (some of the Antisocial Network staff prefer "sad") premise of the show is that a lot of adults aren't "smarter" than the 10-year-olds on the show. Of course, it's all about long-term vs. short- and intermediate-term memory: the adults likely learned the exact same thing the kids know, but in the intervening years the memories have faded. Not so for a 10-year-old who just learned it last week! That's why there's research: google a question on  the 'net and you can find out everything you've forgotten since you were ten. Unless, of course, you're a knowledge-faking freelancer like eHow's Micah McDunnigan. Even that BA in "international relations" (whatever that is) didn't prepare him to expound on "3 Types of Pulleys,"¹ moved from eHow to Hunker (for unknown reasons) by Leaf Group.

Oh, heck, anyone, including McDunnigan, we're sure, can list the three types of pulleys: fixed, movable, compound. There: we're done! but Micah was faced with meeting eHow's vaunted minimum word count (MWC) and their hard-coded format, so he had to use more words. And it's in those "more words" that McDunnigan tangled himself up; tangles such as

"A pulley is defined as being one of the three simple machines: the pulley, the lever, and the inclined plane..."

But wait, Micah: any fifth-grader, even wikipedia (which Demand Media won't allow you to cite [even though it's often more authoritative]) will tell you that there are six simple machines; your three plus the wheel and axle, screw, and wedge. But what do scientists (and fifth-graders) know? Micah has an international relations degree!

McDunnigan, who still hasn't met his MWC, must continue to write, adding bizarre verbiage like "...the pulley's wheel will turn with the rope or chord [sic] that passes through it..." ...getting musical, Micah? and "...a movable pulley will multiple [sic] the force which the user applies to the machine in doing work on an object..." We don't think that's a typo, we think it's a stupid-o. We think so because McDunnigan closes out his content with the monumentally stupid claim,

"The compound pulley system is a combination of fixed and movable pulleys. While this system has the greatest multiplication of user force, the system itself takes up space and involves moving the object a longer distance."

Now there, dear reader, is a classic example of a freelancer holding forth on a topic about which he knows jack shit -- unlike this "experienced freelancer," the average fifth-grader probably knows that the phrase "moving the object a longer distance" is backward. The distance the object must move is the friggin' reason for using a pulley system, so it won't change as pulley types change. What will change is the distance the rope on the other side of the pulley has to move. Here's the real discussion, Micah:

"The mechanical advantage of a pulley multiplies the force applied: if a compound pulley has a mechanical advantage of 3, then you need only apply 50 kg to one end of a rope to lift a 150-kg object on the other end. However, the mechanical advantage means that you must pull 3 meters of rope for every 1 meter you raise the object." Why is that so hard to understand?

For a half-baked answer that starts wrong and just gets worse, the Antisocial Network hereby names Micah McDunnigan our Dumbass of the Day. Take the stipend and buy a clue, OK?

¹ The original has been rewritten by a Leaf Group rewrite specialist, but can still be accessed using the Wayback machine at archive.org. Its URL was   ehow.com/list_7319525_3-types-pulleys.html

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