We had a night meeting/BBQ/nerd fest to watch the fireworks on the 4th of July. We met several hours before it got dark so we had plenty of time to hang out and eat, talk, play chess, and such. The parents did most of the cooking but some of us helped, including putting bread in the oven to warm (more on this later).
Some of us tried to estimate the distance to the fireworks by counting the time delay between the flash and the bang (typical numbers 1-2 seconds, which if we take the speed of sound to be 350 m/s would give a distance of 350m to 700m from our lawn chairs to the apogee. There was some argument about the accuracy of this estimate based on
- the difficulty in estimating duration and
- the possibility that humans aren't very good at consciously judging the relative times of sights & sounds.
One of the guests had a phone app that was supposed to do the calculation automatically (by watching for a spike in the brightness on the camera followed by a spike in volume in the microphone), but it didn't seem to register a sharp enough spike in brightness to give a reliable reading (it was designed for lightening).
After the display there was a great deal of smoke blowing our way. We tried to determine how far up it extended by shining our astronomy laser pointer through the smoke and noticed several interesting things.
We also tried to take cell phone pictures of the fireworks for possible later analysis.
Our invited guests included two college professors (one math, one physics), two math teachers, three engineers, and a scattering of software developers. We got to hear some interesting stories of their exploits with model rocketry and similar which, if true, would not have passed our safety rules.
In all of the confusion a loaf of bread that was warming in the oven got forgotten and left for several hours, yielding an interesting carbon sponge that we may do something with later.