November 20, 2008
Here’s a great video of what happens when you pop a water balloon in space.
This is a nice clear lesson about surface tension and the war between different forces. When you take away gravity, then surface tension is able to hold together a much larger blob of water. It no longer has gravity trying to pull the water blob apart and then air drag breaking it up into droplets.
November 6, 2008
Posted by sciencegeekgirl under Weird Science Tricks
| Tags: physics
Have you seen the videos from the International Space Station on suspended water droplets? NASA Astronaut Don Pettit is the science officer for the mission, and did some fabulous videos on how water (and other liquids) behave in space. They’ve long known about the ability of water to form suspended droplets in space, but he managed to capture droplets in a circle of wire, and then did some great demonstrations for us. Here’s one of the videos:
Why do we get these lovely spherical water droplets in space? You can think of any object as being pulled by a variety of forces, and that’s why it has the shape that it does. The water in the vase by my desk is being shaped by surface tension (creating the little meniscus curve at the edge of the surface), by the force of the walls of the vase pushing in on it, and by gravity pulling it down. So, it takes the shape of the vase, with a flat surface on the top. That’s the best case scenario for it to satisfy all those different forces. You can imagine that if surface tension were stronger than gravity, the water’s surface might not lie flat — instead, it might bulge. Indeed, that’s what happens in space. There is no gravity, and so surface tension wins all the bets. The best way for the drop to keep all its surface as close to the other parts of the surface as possible is to make a sphere (a sphere gives you the minimum surface area for any given volume of stuff).
You can see Don Pettit pick up a drop of tea with his chopsticks, or watch more videos.
Below is what happens when you add an Alkaseltzer to that water droplet.