The Physics of Slingshots 2 | Smarter Every Day 57

I keep wanting to tell Destin that he's gonna shoot his eye out.

But it looks like he still has his predator vision at the end of this video, so that's his business as to whether he wears goggles or not.

At 2:13, Destin shows a graph of the potential and kinetic energy of the ball/band system as the band stretches and releases.

At 4:39, he then uses actual data/video to show that a tapered slingshot band accelerates the bullet faster than does an un-tapered band.

Then, at 5:00, our favorite - the stress-strain curve - shows up.

Sadly, some of the links in the video description to learn more about hysteresis, for example, are dead.

Destin got two videos out of his visit with Jorg (check the slingshot channel for even more). The other video doesn't have as much material science content, but it's still fun, and it shows some momentum and energy calculation with a gigantic slingshot.

COLD HARD SCIENCE: SLAPSHOT Physics in Slow Motion - SmarterEveryDay

Yes, a hockey player with a missing tooth is frighteningly stereotypical.

The sight of the hockey stick at full flex - in motion at about 2:35 - is outstanding...as is the idea that the player likes his stick 'whippier'.

I'm not a hockey player, but I was a tennis player, and I understand the same idea in a different application. Players can choose how much tension they want in their strings when the tennis racket is strung. Stringing at a lower tension allows the ball to deflect the strings more, creating more of a trampoline effect and generating more power. The cost to that is a decrease in control - worse aim - because of that increased power.

Here's a second video going through the same physics - for the first seven minutes anyway. After the first seven, we get a look at the physics of a wrist shot and a hockey player's workout.

Personally, I prefer Destin's enthusiasm.

Modified sponge mops up oil but not water

"Due to the nature of the industry, cost-effective high absorbents are needed...Any advancement to have high spill sorbent is of use." ~ Seshadri Ramkumar

See, what he's saying is that the oil industry (and the shipping industry and pretty much everybody else) spills oil in the ocean...and lakes...and rivers...and fields...so we need to be ready to soak up the oil.

The environmental impact and morals of our modern dependence on fossil fuels aside, the chemistry here is pretty cool.

Though the name of 'compound 1' seems a little odd to me because I can't imagine that the first compound they tried was their successful attempt. There's a reason why we have Formula 409.

Watch glass objects disappear and learn about the index of refraction

Has anybody out there actually been to the Exploratorium out in San Francisco? I assume it's a great science museum, but I've never actually been to San Francisco.

The video above shows an experiment comparing the index of refraction of pyrex (borosilicate glass - the rods that disappear) to that of, I assume, soda lime glass (the rod that stays visible). Pyrex has a nearly identical index of refraction as does corn or vegetable oil (and mineral oil, too). Because of that, Pyrex 'disappears' when soaked in corn oil.

For a slightly more theatrical presentation, check out Steve Spangler's take on the same experiment.



The demo also works with ghost crystals...


I've also heard that it works with colorless gelatin, but I haven't found a video of that, and I haven't tried it at home...yet...