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Re: Gun barrel



Greetings:

The effect of barrel length on muzzle velocity can be convincingly
demonstrated using two lengths of steel tubing and some homemade darts.
I just happen to be performing the demo in class tomorrow.

To perform the demo, find two steel (or other metal) tubes. I haven't
dug mine out the stockroom yet, but I seem to recall that the ones I use
have an I.D. of about 1-1.5 cm. The first tube is about 30 cm long, and
the second is about 1 m. Make the darts by folding some paper into a
cone and sticking a small nail through the bottom. Tape the nail into
place. You'll probably have to trim some paper from the open end of the
cone in order to achieve a proper fit with the tube.

The short blowgun will propel the dart quite slowly a distance of
approximately 3 m (of course this varies greatly with the force of your
blow and the mass of the dart). Using the longer tube, I can send the
dart across the room (maybe 10 m) and easily stick it into a sheetrock
wall (with great accuracy I might add). The students are very impressed.
I relate this to the pictures they've all seen of the blowguns used by
the natives of the Amazon basin. By the way, I've never been able to
resist a demonstration of my "shooting" prowess after the demo is
concluded. The students get a kick out of that too.

-Tim

--
Timothy D. Wilson "A little song, a little dance,
Henry Sibley High School a little seltzer down your pants."
1897 Delaware Ave, W St. Paul, MN -Chuckles the Clown as
wilson@chemsun.chem.umn.edu eulogized by Ted Baxter