Some Physics of the Half-Pipe

Some Physics of the Half-Pipe

What goes down can come back up.

Obviously, the opposite of “What goes up must come down.”

Do I really need to disqualify myself as an expert in half-piping at my age? This is just a introduction to the physics as I, a TV viewer, see it, for other Olympics viewers.

The basic physics is that you go down hill and pick up speed, then you direct it against the sides of the pipe to come to their top. At the start, you first go downhill along the side of the half-pipe or deck, and then turn into the pipe. With good judgement, you come to the lip with excess velocity, so that you can do some twists and flips or rolls.

Since you are still partly pointing downhill when you jump, you have some extra altitude as the lip is falling off downhill as well. With a little inward push, you also have extra distance to fall and maneuver before you hit the side of the pipe.

The top of sides of the pipe have to be vertical, or else you would overshoot out of the pipe, or be thrown back too much toward its center. Hence the exacting name of the “half-pipe”. There is an extended flat bottom, called the “tranny”.  This gives you more downhill to gain more speed, and to compose yourself.

The walls are 22 feet high, and made of polished concrete.  Snowboard half-pipes are actually elliptical in shape.

The highest jump in a half-pipe record is 24 feet 11 inches by Peter Olenick at the Winter X  Games in Aspen, Colorado.

The blue stripes are used as markers to judge your angle to get enough downhill distance and altitude in your next jump, in which to make more maneuvers.

You can’t take too much distance down, or you will not be able to complete the required number of jumps.  The Olympics half-pipe is extra long to allow for another one or two jumps.

If you don’t fully rotate a turn, instead of your board heading down and across the pipe, it will land parallel to the side, encounter enough resistance to stop you, and your rear will fall on the side, disqualifying that run.

So to have successful runs, you must have practice and experience. But you also have to adapt to the hardness or softness of the snow, the wind, and your injuries. You also have to adjust your spins or flips to the amount of height that you have, and your angle if you need to gain more height at your next maneuver.

If you are out of control, just like in ordinary snowboarding, you can turn perpendicular to the slope and come down slowly.

Remember, this is for viewers. If you are going to run the half-pipe, train with a professional.

About Dennis SILVERMAN

I am a retired Professor of Physics and Astronomy at U C Irvine. For a decade I have been active in learning about energy and the environment, and in lecturing and attending classes at the Osher Lifelong Learning Institute (OLLI) at UC Irvine.
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