Mesa Mike's Midden of Musings

I've got the "Hamster Dance" song circulating through my head, and it won't go away!
Is there a therapist in the house?

Well this sometimes happens when there's a threesome involved. Somebody gets jealous, an argument ensues, then..., then... well, just look at what happens next!

Such a shame.

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Well, this is embarrassing.

I went out into the wilderness today and found just the right spot to hide my latest geocache. While I was at the cache site, I decided to get a notebook out of my backpack in order to write a few things down. As I was doing that, I noticed I had some data sheets for some triangulation station benchmarks that I was planning on trying to find some day.

Being the geek that I am, I got sidetracked, and grabbed my calculator and did some trig calculations using the coordinates of some of the triangulation stations and the new cache. These calculations seemed interesting at the time...

Anyway, after a while I headed back to the car and went home to enter the coordinates for the cache. But to my horror, I discovered that I had completely forgotten to mark a way point at the cache site! I went back to the area, but couldn't find it. I just couldn't remember exactly where I put it. I searched my notebook, but there was nothing among my chicken scratches that makes any sense now, except for this crude drawing I made while at the cache site:



Please, can you all help me locate my lost geocache?

If you do find it, please log it at GC1B0Q9.

More and more often, I'm seeing people write or say such things as, "So and So passed last Friday" to mean that So and So had just died. I'm not confused by such usage, but it still grates on my sensibilities.

Please, folks, the phrase is "passed away," or even, "passed on" when you are referring to the death of someone. When you say only that "he passed," it makes my mind, for a short while, imagine all kinds of qualifications on the phrase to narrow down the meaning. "Passed" what? Passed by? Passed out? Passed the biscuits? Passed a kidney stone? Passed gas?

Finally, my mind settles on passed AWAY, but only after having traumatized me by forcing me to think of all the possible meanings.

Taking an Internet phenomenon to the next level.
With a healthy slathering of Kiwi layered on top.

Remember back in the '80s when Ronald Wilson Reagan was determined to be the Antichrist, because there were 6 letters in each of his first, middle and last names?

Using the same numerological analysis, I have determined that the number of Barak Hussein Obama is 575, thus he is a Haiku.



OK, well that was clever for a few minutes. Until I realized that 'Barak' is actually spelled, 'Barack'. Kinda messes up the numerology, a bit.

So. Nevermind.

As predicted, of course. The Mythbusters proved it in last night's show.

There has been lots of discussion on the internet about whether an airplane on a conveyor belt could take off, if the conveyor belt moved in the opposite direction at the same speed as the airplane. The problem is usually stated something like this:

"A plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction). Can the plane take off?"

The people who say no, typically reason that for an airplane to take off, it needs airflow over the wings (more than just the amount the propeller blows), but since the airplane can't move forward, there is no airflow over the wings, therefore the airplane can't take off.

But this begs the question. Of course the airplane needs to move forward at a speed great enough to supply the lift in order to take off. That's kind of integral to the idea of "taking off." Whether the airplane can do so is exactly the question we are being asked, I think.

The faulty assumption is that the contraption is designed to prevent the airplane from gaining forward speed. That, however, is not stated in the problem. People make this assumption, I guess, by analogy to walking on a tread mill where one does not go forward, but stays in one spot as the treadmill goes backward at the same speed one is walking forward.

But airplanes don't propel themselves forward by pushing against the ground (or the treadmill in this case) like walking people or cars do. Airplanes' forward thrust comes from the "equal and opposite reaction" of the action of throwing stuff backwards (air, in the case of a propeller plane, or the hot expanding gases of spent fuel in the case of a rocket).

It amazes me that so many people just don't get it, even after having it explained and demonstrated. Many of them claim that the Mythbusters experiment was flawed, because "the plane actually did move forward!" For some reason, they thought that the "wheel speed" of the plane was to match the conveyor belt speed. But the original question only says that the speed of the conveyor belt matches the speed of the plane.

The assumption that the "speed of the plane" means it's wheel speed relative to the belt is an unwarranted assumption, in my opinion. Unwarranted, because it makes the original question illogical. The only way for the wheel speed to match the belt speed is for neither the plane nor the belt to be moving at all; or for the plane's engines to be providing just enough thrust to match the very minimal force of the wheel friction in order to keep it from being dragged backwards. But the question is, "can the plane take off?" This implies that the plane should be trying to take off, which means full thrust, not just minimal or no thrust. So it must be that the "speed of the plane" must be relative to the ground.


For your amusement, see the comments on The Mythbusters forum.
Other comments are at Kottke's nice discussion of the puzzle.

Oh, and I just discovered this definitive analysis of the question.