Engineering is cool #1 – Machine in Concrete

Machine in Concrete

We took Rose to The Exploritorium last week for the first time.  Oh my.  She was like a kid in a candy store.  So many things to play with!  At 5, she isn’t quite ready to hear “how” everything work (she pretty much ignored us when we tried to explain it. lol) but completely enjoyed manipulating everything.  If you are ever in San Francisco with your kids (or even without them), go there.  Seriously, go there.  It’s filled with tons of examples of interesting science/physics/engineering with easy to understand explanations of “why”.

I was in engineering heaven.

Out of the literally hundreds of exhibits, the Machine in Concrete fascinated me the most.  The motor runs at 200 rpm but after 12 pairs of worm gears which reduce the speed by 1/50th for each gear, the output shaft rotates so slowly, it will not make a full rotation for 13.7 billion years.  Yes, you read that right, 13.7 BILLION years.  Whoa.  The output shaft was able to be encased in concrete with no stress on the drive train.  Seriously….whoa.

Engineering is cool ya’ll.

Just for fun, I found a guy on Reddit that did the calculation for what would happen if worm gears worked in the opposite direction (they don’t so you can’t turn the output shaft and the anything turn on the drive train so this is a hypothetical calculation).  Have I mentioned I love engineering?

“And even if you ignore the worm gear issue, if you turn the final gear at 1mm/s, the first gear will move at 814365469 times the speed of light. [5012 / (c * 1000) = 5012 / 299 792 458 000 = 814365469]

To make something move at the speed of light you need an infinite amount of energy. So if you try to turn the final gear there will be a high amount of resistance, infinite to be exact, because the first gear can’t turn that fast. It’s almost like the first gear is now also trapped in concrete (although this is a speed restriction and not a movement restriction), except that concrete is made of “Unobtainium” and cannot break. (The gears will also have to be made of Unobtainium because they will strip long before you reach the speed of light.)

Staying with the same scenario you should be able to turn the final gear at 0.12 picometers/second and the first gear will turn at only 0.1 times the speed of light. (The radius of hydrogen atom is 25 picometers.)

EDIT: The energy needed to get the first gear up to 0.12 picometers/second (assume no friction) would be about 1.12*1015 Joules or 1.5 Hiroshima nukes.”

1 Comment

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One Response to Engineering is cool #1 – Machine in Concrete

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