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Written by river95
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Tuesday, 01 April 2008 |
Plane on a Conveyor Belt
Episode # 97
Original Air Date: January 30, 2008
Plane on a Conveyor Belt
The Myth (as Adam explains it): “Normally, a plane sits on a runway, spins up its engines, moves forward, gets enough air over the wings, and takes off. But in this case, the plane is sitting, not on a runway, but on a huge conveyor belt that is matching the plane’s forward speed in reverse. The grand question is: Can the plane take off? The myth is that it can’t.”
The Experts: Mark Johnson, who is the pilot of the ultralight plane, thinks that the plane will not take off.
Memorable/Quotable Moments:
Jamie: I don’t know if I can handle this, actually. (referring to the model plane they are getting ready to fly) We’re…we’re using this particular item the way that it was intended!
The Action/Results:
First, Jamie and Adam get some plane flying lessons from Grant. Then, they set the treadmill up to the exact speed that the plane needs to take off – 11.3 miles per hour. They put the plane on the treadmill, get it up to speed, rev up the engine of the plane, and the plane goes forward – off the edge of the treadmill and onto the floor. However, they decide that this is because the plane needs more distance in which to take off. So, they modify their design by having Adam drag a twenty-foot length of butcher paper behind his Segway, and put the plane on that. After a few trials, it finally works! The plane does take off from the treadmill as it is going in the opposite direction at the same speed. Then it is time for the full-scale test!
At the runway, Adam and Jamie found that the plane needed 85 feet of runway and a speed of 25 miles per hour to take off. Then they hauled out a 2000-foot long tarp, hooked it to the back of Jamie’s truck, and tested it. Adam hopped on it and started to run, thinking that he was being funny, but he was ripping holes in it by accident instead. Then the wind came up, sending the tarp flying, and they had to push the experiment back to the following morning.
The next morning, they set up the tarp, got the plane on it, and were ready to proceed. The pilot got the ok from the tower, and Adam told Jamie to hit the gas! The truck pulled the tarp in one direction and the plane went off in the other direction. Suddenly, the plane was airborne! It took off normally, and it put an end to this myth. This myth is BUSTED – a plane can and will take off from a conveyor belt going in the opposite direction but the same speed as the plane.
Science Content:
Jamie, Adam, and Rob explain that a car will appear to be stationary on a treadmill, because the car’s tires are the things that are causing it to move forward. The treadmill is moving backwards, and so the net result is no movement. However, a plane is being moved forward by its propeller, and so the treadmill does not affect the forward motion at all.
Cockroach Survival
The Myth: In the event of a nuclear explosion, the cockroaches will be the only things still living.
The Experts: Michelle Johnson, who is a Certified Health Physicist from the Pacific Northwest Laboratory, explains to Tory exactly how much radiation they will be using on the bugs.
Memorable/Quotable Moments:
Tory: (talking about what they are going to do to the insects) Science is fun, but it’s not always nice!
The Action/Results:
Tory, Kari and Grant decide to use three types of insects, rather than just one, so they have some basis for comparison. Accordingly, they get cockroaches, fruit flies, and flour beetles set up in Plexiglas boxes, and take them to the lab. There, they expose batches of the bugs to three different radiation levels – 1,000 rads, 10,000 rads, and 100, 000 rads. The insects all seem to be pretty healthy after the initial dose of radiation, until they get to the 100,000 rad level. At that point, 90% of the cockroaches die. However, they pack the bugs back up, and take them home to be monitored. They will check them at 15 days after the experiment, and also at 30 days after the experiment, to see how many are still alive.
After 30 days, all the results are in. 30% of the cockroaches survived 10,000 rads, and 50% of them survived 1,000 rads. However, none of the cockroaches survived the 100,000 rad dose. One of the flour beetles did survive that dose, however. So, the end result is that, while all of the bugs survived doses of radiation that would kill a human, there are bugs that would survive a nuclear explosion better than a cockroach. This myth is BUSTED!
Science Content:
Kari and Grant talk about the fact that Henri Becquerel first discovered radiation, but that people are still studying it today. Tissues in our bone marrow and intestines are more susceptible to radiation than tissues in simpler living things, like bugs, which might explain why we can handle lower doses of radiation than they can.
Shaving Foam Shenanigans
The Myth: If you take a can of shaving foam, freeze it, then cut the can off, and put it in someone’s car, you will end up with a whole car full of foam.
The Experts: Kari, Grant, and Tory
Memorable/Quotable Moments:
Grant: This isn’t a prank – it’s a minor inconvenience!
The Action/Results:
First, they try the myth as it has been heard – with one can of shaving cream. It expands a bit, but it doesn’t even fill the whole front seat. Then they ramp it up and try it with 50 frozen cans of shaving cream. The resulting foam fills over half of the back seat cushions. So, they decide to ramp it up again, and use AB foam. This is polystyrene foam that expands very quickly. Adam used it to seal the windows of the plane in “Explosive Decompression”. So, they mix up 25 gallons of AB foam and put it in the car. It quickly expands to fill the entire car, and starts to leak out the bottom. Kari demonstrates, by hitting a window with a hammer, that the foam is indeed solid, and has solidly filled the car. This myth is BUSTED!
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Episode Descriptions 
