Banana Physics

Yesterday I presented a talk at ICT Conference for Schools, in Southampton. We're (hopefully) going to be presenting something similar in Boston this summer. I thought it would be good to just summarise it here, and post the code examples I showed.

Banana Physics starts with the Banana Piano - the classic Makey Makey project... or should I say the ONLY Makey Makey project. Despite their claim its an "invention kit" which can "make anything", their idea of "anything" is rather limited to being a keyboard made out of fruit! More or less any fruit you'd like!

In addition to being limited, we don't actually learn anything from the piano project. It's fun (for a few minutes), but what are we trying to teach? That Banana's are fun? The best thing we might learn is that Banana's conduct electricity... 

Except they basically don't. To understand we need to investigate RESISTANCE. If we use a pico board, instead or a makey makey we can actually do science!

This is the circuit that the pico board (and pretty much everything else) uses to attach your banana to the computer. R1=10K, and the banana replaces R2. With a bit of good old school Ohm's law, we can write an equation to calculate R. It turns out the Banana's have a resistance of around 40K-50K ohms. Not good conductors at all.

The next step is to drop a thermistor in place of R2. With a bit more complex maths, we can turn that resistance into a pretty accurate temperature (or up to 4 different temperatures on the different channels). It's pretty easy to log that data over time. On the one hand Picoboards aren't cheap (about £30 in the UK), that's really nothing compared what you'd pay for a 4 channel data logger, or even a good multimeter.

We then switch out the thermistor for a light dependant resistor. We could track light levels, but we can also use it to detect an object moving in front of the sensor. We set up two about 70cm apart, and time a beanbag to fall from the top one to the bottom one. Applying kinetic equations we know starting speed (0m/s), distance (0.7m), and we measure time. Which allows us to calculate acceleration - gravity.

Alternatively we can use the Lego Wedo... Two distance sensors make a great speed trap, so we can measure the speed of an object. If we drop the beanbag 70cm, and measure its final speed, kinetic equations will give us gravity again. In the talk I just did a very casual demo, and dropped it from a very rough distance, and it came up with a value of 8.5m/s/s. Pretty good.

The final demo was using the wedo tilt to measure the period of a pendulum. Again putting together  a bit of maths/physics, and coding I got a value of 10.5 this time. Again, this is pretty good for a guy standing in a room with a laptop and a few bits of Lego.

Here's the code I used for the demos. Check out the "Science" tag on my blog posts, to get more detail on these projects (perhaps built with different hardware), and ideas for other code based science.

The point of the talk was (in addition to promoting Sniff!), to show how using coding and making you can make high school science really fun. If coding is writing, then the whole point of learning to code is to unlock new ways of expressing and exploring. If coding just lives in the ICT class then its a total waste of time. If it lets you explore and understand the universe better, then that's pretty amazing.