So this Bullet Runs Into an Egg...

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With high speed photography, I can use a high voltage spark to create a flash of only 1/1,000,000th of a second in duration. The problem is that there are not a lot of things that move this fast that such a flash is required to stop the motion. Bullets are such a subject requiring a very high speed flash system. Around the lab we jokingly call this "ludicrous speed". After photographing bullets hit just about every conceivable object it is time to move on to other subjects. In this case a paint ball is sent into the edge of a straight razor blade. The paint ball crosses two optical detectors that measure the velocity (166 feet per second) then trigger the flash when the paint ball has traveled about 12 inches. The momentum of the paint ball keeps the ball in motion even after being sliced in half by the razor blade. A wonderful way to illustrate Newton's Law of Inertia - that is, an object in motion will stay in motion until a suitable force is applied to stop it.

With many photo sessions once the photography is done we will stand around looking at all the equipment set up and wonder what else we can do with it before the set has to be disassembled. At this point someone wondered what would happen if the paint ball were to hit an egg?

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The results above show that the paint ball hits at such a speed as to break, then force the yolk out the other side before moving through the rest of the shell. Shots like this create a tremendous mess and parts of the lab will have pinhead specks of pink paint ball dye and dried egg yolk for years to come. I hope this image excites the minds of a few readers. I always welcome ideas, even though it is often years before I get around to doing a certain project.

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This post was written by Ted Kinsman for Photo Synthesis.

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Two comments:
SWEET!

I'll be checking back here often.

One question: How long do setups like the two in this post take?

Oh, my children will enjoy this so. The mess was worth it, vicariously at least! Thanks for performing this important scientific cleanup for the rest of us to learn from.

The paintball/egg shot reminds me of the action of an APDS (Armour Piercing Discarding Sabot) tank shell, a kinetic energy projectile, which is designed to first penetrate the opposing tank's armor (with a tungsten carbide penetrator) but then still have enough force to force the internal metal frame of the enemy tank into the space within in much the same way the yolk was forced out before the paintball had fully penetrated the egg itself. The "sub projectile" (discarded from the sabot) does the damage by shocking the internal structure of the enemy tank.

Since you "welcome ideas": I would love to see high-speed photography of a large rubber-band ball (baseball or softball size) being split by a blade (samurai sword? a large razor would do fine too :) I think it would be interesting to see all of the individual rubber-bands releasing their stored energy all at once.

By automandc (not verified) on 07 Oct 2009 #permalink

hmmm, nice idea automandc, however is it really "stored energy"?

Surely we are really talking about the "conservation of energy" transforming potential energy into kinetic? Presumably there will also be a number of confounding variables going on inside the rubber like entropy, temperature, vibration rates, and amplitudes.

It appears that the paint is under high pressure and cannot emerge without a great deal of turbulence. Unlike the contents of the egg, the exploding paint has no obvious symmetries. To my eye at least, the egg is beautiful and the paintball ugly.

Unlike the contents of the egg, the exploding paint has no obvious symmetries. To my eye at least, the egg is beautiful and the paintball ugly. thanks...very ice..

Since you "welcome ideas": I would love to see high-speed photography of a large rubber-band ball (baseball or softball size) being split by a blade (samurai sword? a large razor would do fine too :) I think it would be interesting to see all of the individual rubber-bands releasing their stored energy all at once.