PURPOSE: To illustrate inertia of motion.
DESCRIPTION: A pencil is accelerated to almost the speed of sound by blasting it through a four-foot tube using a carbon dioxide fire extinguisher. The pencil will readily impale itself on a piece of 3/8" plywood. With a little bit of luck the pencil point will be virtually intact, although sometimes you need to re-sharpen it after the demonstration.
SUGGESTIONS: CAUTION: Be sure that the hose fitting is securely attached to the tube and that the plastic shield is in place before firing. This is potentially a dangerous demonstration.
REFERENCES: (PIRA 1F30.50)
EQUIPMENT: Cart with pencil blowgun tube and fire extinguisher with required fittings, sharpened No. 4 pencils, 4"x4" squares of 3/8" plywood, as photographed.
SETUP TIME: None.
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