Archive for February, 2011

What great tools are Blogs and Twitter! I twitted about my previous blog post “Blowing Head!” and on the second day, after about 150 people had read the post and left positive comments (not all 150 actually), I get a Tweet back from Ashley Kent (@AshleyKent), who not only too the time to read my post, but also pointed out that NASA research suggests that a human body would not explode, or freeze immediately, in Space. Ashley gave me this link that explains some of these findings and tests made by NASA.

My previous post doesn’t mention exploding bodies actually, it just asks questions, so I could just tell you that of course I knew, but I would be lying. It was an interesting surprise to me to find out what NASA  has discovered and predicted. However, there are some effects of exposure of a human body to vacuum which resemble what happens in tea cake in the vacuum coffee saver, as suggested by this article. An interesting part of the article says:

“When the human body is suddenly exposed to the vacuum of space, a number of injuries begin to occur immediately. Though they are relatively minor at first, they accumulate rapidly into a life-threatening combination. The first effect is the expansion of gases within the lungs and digestive tract due to the reduction of external pressure. A victim of explosive decompression greatly increases their chances of survival simply by exhaling within the first few seconds, otherwise death is likely to occur once the lungs rupture and spill bubbles of air into the circulatory system. Such a life-saving exhalation might be due to a shout of surprise, though it would naturally go unheard where there is no air to carry it.

In the absence of atmospheric pressure water will spontaneously convert into vapor, which would cause the moisture in a victim’s mouth and eyes to quickly boil away. The same effect would cause water in the muscles and soft tissues of the body to evaporate, prompting some parts of the body to swell to twice their usual size after a few moments. This bloating may result in some superficial bruising due to broken capillaries, but it would not be sufficient to break the skin.”

So, it might not be as dramatic as it looks in the demo in my previous blog post, but the demo is certainly a very interesting activity that could be turned into a great investigation of the effects of a vacuum on different materials and tissues. We have the opportunity here to do some real Science with our kids and pose some questions that will really challenge their experience and create a metacognitive conflict, which will make the activity even more interesting and enjoyable for them!

Any suggestions on the things we could stick inside this coffee saver vacuum chamber? What about simulating a lung in vacuum with a balloon? Where is the limitation of this analogy? What would happen if the balloon were filled with water? Please make your suggestions…

This blog post is about a great demonstration I got from David Featonby from the Institute of Physics and a little adaptation I thought about after seeing his version. He tipped us all up on a really cool vacuum container to store coffee which you can find here. Then, he put a teddy bear shaped marshmallow in, closed the lid and sucked the air out. The effect is really dramatic as you see the teddy bear mallow increasing in size and become “huge”. My boys think it is a Humongous Mallow (only avid Ben 10 fans will understand the reference).

Anyway, the advantage of using this container instead of a normal empty bottle of wine is that you can put much bigger things inside and that’s where I thought of this additional demo to do with this device. There are various ways in which you could introduce the demo. For example, you could watch a bit of a scientifically questionable Sci-fi film and ask your kids “Is it possible?” The clip I have in mind is Star Wars: The Empire Strikes Back, when Han Solo hides the Millenium Falcon inside an Asteroid cave (which turns to be a giant worm’s belly). In that part of the film the crew goes out of the spaceship wearing their normal clothes and just a tiny breathing mask, as if 🙂

The point here is that if Han Solo and friends were on an asteroid in outer space, they would be surrounded by almost perfect vacuum and their internal body pressure would cause them to pop as soon as they get out of the ship! So, what would your students think? Would they believe it is possible?  Would they think they would just freeze?

At this point you can show your coffee saver and put a tea cake inside. Then, ask the kids what they think would happen if we could take most of the air out!

And see their faces as this happens!

You can now go back and ask the same question from the Star Wars clip. Is it possible? What would happen to Han Solo and his crew?

Please, see my next blog post as there is an interesting update pointed out by Ashley Kent (@AshleyKent) that suggests that your body wouldn’t actually blow up in space! So, the demo is becoming even more interesting and pedagogically really valuable, as we have the opportunity to really confuse our kids up to then let them construct a new and stronger meaning. This is active Constructivism and Metacognitive Conflict brought to its extremes 😉

Thank you Ashley for pointing this out!