The Physics of Superheroes!

Have you ever read a superheroes comic? Watched a superheroes cartoon, or at least watched one of the great Marvel movies? I bet you have done one of these at least once. If you ask you pupils, most of them would go to the cinema to watch these films as soon as they are out and would really enjoy them! What a great opportunity to get some Physics in it.

You might think, what Physics? Superheroes defy Physics and would just reinforce silly misconceptions. And that’s where we need to ask a different question, i.e. what would need to happen in this situation, or with this superhero, to be physically possible?

A good example is X-men 3 (DVD only £3 in Tesco). You can use this very popular film to introduce Momentum. The Juggernaut has a very cool power, i.e. “If he builds any momentum, nothing can stop him”. This sentence is in the maximum security lorry scene, when the Juggernaut gets freed. This power can be used to generate interest in momentum. The Juggernaut had to be confined by being tightly bound with extra strong metal restraints, so you can immediately ask: “What do you think momentum depends on?” Obviously, he cannot be allowed to move, or we would build momentum and become unstoppable. So, momentum depends on the velocity of the Juggernaut. What else then? Well, just look at the guy! He is massive, so momentum also depends on the mass of the Juggernaut. Great you can now introduce the momentum equation.

In the last fight you can add juice to the lesson and make momentum really memorable, although you might also want to mute the rather unkind name this villain gives to Kitty. Here the Juggernaut is featured in an amazing scene where he smashes through lots of people, heavy vehicles and walls, so again you can reinforce the concept by asking what causes the Juggernaut to build so much momentum. Get the kids to think about different ideas, e.g. is it his speed? He doesn’t seem particularly fast when he goes through walls, so it must be his mass. But, although he’s very big, he doesn’t really look like a huge giant. What should happen in the Juggernaut body to make this physically possible? Well, he probably has the ability to change the density of molecules in his body, so that his mass increases greatly and he can build enormous momentum and smash into things.

When he eventually tries to crash into Kitty and the “Cure” , they dodge and the Juggernaut (who actually is quite stupid) crashes into the wall and falls unconscious, because the “Cure” is the boy who has the power of taking away the powers of any mutant who is near him. So, the mass of the Juggernaut must have become less here…

I hope you like this idea and you will share other ideas on the Physics of Superheroes. Please, let me know if you will use this idea and how your pupils responded to it!

Convection Crazy!

Here is a lovely classroom demonstration that I saw at the ASE Conference 2010 in Nottingham. The demo was part of the Physics Education Lecture, which displayed the best of the PhysEd magazine. I really learned a lot and was well impressed by the quality and creativity of the demonstrations, activities and workshops proposed by the Institute of Physics. As one of the IoP Network Coordinators I was very proud to be part of the Institute and see how many outstanding workshops and lectures they put together for the event. Apparently, the IoP did the majority of workshops and they were all free of charge, although the conference was organised by the ASE.

Anyway, coming back to our demonstration. At the lecture it was shown using two small glasses, so when I went back to my lab I thought; “What would happen, if I use two very tall columns of water? And this was the result!

So, why won’t the two liquids mix?

I put cold water in the bottom column with some blue food colouring and boiling hot water in the top column with some red food colouring. The tricky bit is how to turn the top column upside down, as it is really hot and heavy, but it was well worth it! So, I put a sheet of paper on the top and then carefully turned it upside down (you might need a helper to do this). Then, I placed the top column on bottom one and as you can see, and unlike what the kids would expect, the red and blue water don’t mix. They actually stay unmixed for a very long time (over an hour at least).

But how do we explain such an effective phenomenon? Well, the hot water is less dense than the cold water at the bottom, as its particles have more kinetic energy, hence moving further apart from each other. The result is that we have two liquids of different density, with the less dense one at the top, which therefore will float on top of the denser cold water. It is a bit like having oil and water, you can tell your students!

This is a really nice demonstration that will really help your pupils to understand that hot liquid rises and cold liquid falls. It’s not only very memorable, but it also shows quite clearly that in heat convection currents it’s not the “heat” that rises, but the hot liquid, or gas.