Amazing bouncing water droplets

[Chip]

I didn't know a drop of water could do this:

http://www.flixxy.com/water-drop.htm

[cosmocrazy]

Yeah its truly amazing when you see something like this. We take things for granted so often that we are unaware of the processes involved. I find surface tension to be quite an amazing and even know a good trick which involves it

[Swift]

I seen similar demonstrations, but a very cool, and nicely done video.

[Beagle 2's Parachute Cord]

Ever tried pushing a polystyrene ("styrofoam") cup of tea across a desk so it sticks and slips rapidly and vibrates? You can get loads of droplets rolling around on the surface of the tea.

There's a rather unimpressive video here: http://www.thenakedscientists.com/HT...up-fountain-1/

But if you get the speed right you can get a standing pattern with drops floating on a cushion of air for several seconds. I find tea works better than water

[Swift]

I find tea works better than water

I suspect that some of the organic materials in tea act to increase the surface tension, and/or to stabilize the droplets. Other agents, such as ethanol or various soaps, would have the opposite effect and would decrease the surface tension and destabilize the droplets.

[dhd40]

I suspect that some of the organic materials in tea act to increase the surface tension,

(my bold)
AFAIK, the only liquid with a surface tension higher than that of water is Hg (mercury). Increasing the surface tension of water, therefore, seems to be impossible. Am I mistaken?

[Swift]

Thinking about it a little more, for pure liquids, I think you are correct. But for some aqueous solutions, you can go higher. For example, in this wikipedia table, you can see that concentrated sugar and salt solutions are higher. On the flip side, increasing temperature drives it down. Maybe B2PC drinks their tea very cool and very sweet.

[rommel543]

What I like seeing is when you drip water onto a hot grill and it causes the water drop to dance around. I grew up with a wood stove in our house (kind of like this). When it got nice and hot we used to drip water on it for fun.

[Swift]

You can do that with a frying pan on the stove. It is the layer of steam that forms between the droplet and the hot grill, as opposed to the trapped air in the OP's video.

And yes, I've done it too.

[weatherc]

You can do that with a frying pan on the stove. It is the layer of steam that forms between the droplet and the hot grill, as opposed to the trapped air in the OP's video.

And yes, I've done it too.

Supposedly this is how you can tell when the pan is the right temperature for cooking pancakes. If the water evaporates without dancing, it's too hot; if it doesn't dance, it's not hot enough.

Of course, when I'm cooking pancakes I use an electric griddle with a thermostat, so it's not a technique I use anyway.

[dhd40]

Thinking about it a little more, for pure liquids, I think you are correct. But for some aqueous solutions, you can go higher. For example, in this wikipedia table, you can see that concentrated sugar and salt solutions are higher.

I see, wasn't aware of this. Thanks

Maybe B2PC drinks their tea very cool and very sweet.

Obviously