Balloon that blew my mind
Last week I was running a workshop in the next room to Geoff Neuss who was running a similar one for Chemistry teachers. I was doing a design experiment exercise with particular focus on the learner profile, the participants were coming up with some good research questions. During one of the breaks I mentioned the exercise to Geoff and he came up with the idea of measuring the temperature as the balloon was popped. I was a bit sceptical, thinking that the temperature sensor wouldn't respond fast enough. I was quickly put in my place by a participant who criticized me for not being open minded. Touché. After that we of course had to do it and got some interesting results. I chose the little sensor that comes wih the Pasco GLX. It's small size making it respond quickly. We put the sensor in a balloon, blew it up and popped it. The results are shown. Firstly the temperature rises as the warm air is blown into the balloon. Then it begins to fall as the warm air cools down. When popped there is a sudden rise followed by a drop. Maybe the rise is due to the balloon being compresses before the point penetrates the rubber? I can see I'm going to have to do this again.
I've now done a second experiment to find out whether that peak could be due to me compressing the balloon. It appears that it's not. I squashed the balloon and hit it on the table but got no response from the thermometer.