There’s a class of materials that become more viscous as you apply more force. Silly putty, Crazy Aaron’s Thinking Putty (which I have in my hands right now), and oobleck (cornstarch and water).
When you prod them with your fingers, they act like dough. Hit them hard, and they don’t deform at all. They bounce if you throw them at something. You can tear or snap them with quick movements.
So, I’m wondering what would happen if you fired a bullet at one of these materials. Let’s say you made it into a square block and put it up against a brick wall so that it couldn’t go anywhere. Would the bullet bounce off? Would it flatten against the putty? Would it shatter?
A lab I worked in once had a volleyball-sized block of silly putty that I frequently had the opportunity to play with. One of my experiments involved hitting a fist-sized hunk of it with a hammer, and the result was that it just shattered into a million pieces that flew everywhere. It was really bizarre. Stabbing the putty quickly and forcefully with a large philips-head screwdriver results in the screwdriver penetrating the block, but with a very satisfying rip instead the normal deformation you get when stabbing it slowly. I’m guessing a bullet would have enough energy that it would act more like the hammer, but I suppose it’s possible that a large enough block of putty would just have a hole ripped into it and swallow the bullet.
Oh, and it’s very satisfying to bounce a volleyball-sized ball of silly putty, but it’s really hard to get it round enough to bounce it controllably. The stuff is really hard to shape in large quantities.
Another vote for Crazy Aaron’s, BTW. I have a can of ‘scarab’ and a can of ‘oil slick’ in my office. My expert opinion ( ) is that it actually holds up to a lot of handling better than the generic coral-colored putty we had in the lab (which was not technically silly putty, but the raw stuff silly putty is made of, ordered in bulk from Dow Chemical), which got quite a bit softer as it got old. I’ve had my Thinking Putty for at least 4 years and it seems to be as good as new.
Damn! I wish you’d asked this a year ago. I was working in a place that had a ballistic test setup that I could’ve used. We probably could’ve sold tickets for something like this.
Too late now. It’s all been carted up and packed away.
'Nother vote for the THinking Putty. I’ve got a couple tins of Aura and Oil Slick in here, and they’re great for working over when thinking or you need to take a break and exercise your hands and wrists.
Or as a warning. “Watch out or I will CRUSH YOU like this ball of putty here, see?”
Silly Putty is, I think, a high molecular weight polydimethylsiloxane, a compound trademarked by General Electric as “Silicone”. The way it works inside is that the molecules will rearrange themselves at a certain pace, that is their stresses decay exponentially with a certain relaxation time, which is fast enough to accomodate what you do with it in your hands. But at higher rates they don’t rearrange themselves and behave elastically instead. So in the time domain of a second or more it is viscous, but in the time domain of 10 milliseconds or less it is elastic. Another polydimethylsiloxane is the “Silicone rubber” sealant you buy in tubes for caulking bathtubs etc. In the tube, it’s a heavy sticky viscous goo. But if you tap on the side of the tube you will hear it ring, because these vibrations are too brief for it to reshape viscously and it acts elastically instead.
Original Silly Putty (accept no imitations) in 5 lb blocks can be bought here. That’s the Crayola Store if the link doesn’t work. Note the kind that changes color when handled; it might be interesting to see what color that stuff turns when shot. Just play safely, kids.
) is that it actually holds up to a lot of handling better than the generic coral-colored putty we had in the lab (which was not technically silly putty, but the raw stuff silly putty is made of, ordered in bulk from Dow Chemical), which got quite a bit softer as it got old. I’ve had my Thinking Putty for at least 4 years and it seems to be as good as new.