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Old June 6 2013, 03:11 AM   #53
Christopher
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Re: MYTHBUSTERS 10th Anniversary Season

Motorcycle skimming on lake: I was surprised when the wheel actually rose up to skim on the water on that test with the speedboat. But even so, I could immediately see why it wouldn't work the same way with the actual motorcycle, because the vehicle would have to retain that speed. The wheel hanging off the boat could retain that speed because something else was actually propelling the boat. But motorcycle wheels on water wouldn't have enough traction to keep up the cycle's velocity, so even if it skimmed for a couple of moments, it would rapidly slow and sink.

I was surprised that it worked at all, even for 50 to 100 feet, but I guess that was just momentum. And I don't think Jamie's 300-foot ride proves that the bike was able to exert thrust to stay in motion. For one thing, in the previous test, the rear wheel was skipping on the surface like a stone, meaning it would only intermittently be in contact with the surface, not good for generating thrust. For another, I bet if you were driving a bike at 80 MPH and shut off the motor, you could probably coast for 300 feet easily. So while they confirmed the basic myth, I don't think they resolved the question of coasting vs. thrust.

I'm still a little unclear on the physics of just how the spinning wheels kept the bike afloat. I wish they'd talked about that. I guess it's that as the wheels spun, new portions of them kept hitting the water and meeting surface tension, and by the time that gave way, the wheel had moved on and a different portion was now meeting the water. Kind of the same principle as the Jesus lizard running across the water -- it's sinking a little with every step, but takes new steps so fast that it doesn't sink very far each time.

These days, the show tends to do a brief 30-second segment in the middle of the commercials between the final two acts. This time I was disappointed that the bonus segment was essentially a commercial itself, with Jamie extoling the virtues of that brand of motocross bike.


Hotel room parachute: This was an unusual category of "myth" for the show: something that someone actually thought might work, but never got the chance to test. Although as the gang's tests showed, the criminal was lucky he got arrested before he attempted to use his parachute. (But they missed the chance to say "It's curtains for Buster.")

As for the final big parachute, I was surprised at how quickly it decelerated Buster to a survivable landing. I would've expected it to be more gradual than that. I'm a little disappointed that they didn't test it against a real parachute for a baseline comparison.

Speaking of baselines, in the first test, did they really need to drop Buster without a chute as a control? Don't they have plenty of data for how hard Buster hits when falling from a variety of heights? Although I guess this iteration of Buster may not have weighed quite the same or had quite the same air resistance as his predecessors; for one thing, most of his head was missing.
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