Category: STEM work

It’s interesting and illuminating to get the data and make one’s own sketch.  I annotated each link with the half-life and the nature and energy of the particles emitted (yes, let’s be quantum-mechanical and call gamma ray photons as particles). The end of the chain wouldn’t fit on one page, so there’s a second page, on which I scribbled information on a number of radionuclides. The featured image has, of course, nothing to do with radioactivity other than showing something in the natural world, but it’s interesting. Hippos are a real hazard to people who live near them!

Second page:

Our students in grades 4-7 at the Las Cruces Academy, our non-profit private school, enjoyed tracking the decolorization of phenolphtalein by hydroxide ion.  Phenolphthalein is that beautiful rose-pink indicator dye used in acid-base titrations.  It changes structure a bit in base but then slowly undergoes a permanent decolorization.  The kinetics (rate and order of reaction) are interesting and fun to follow.  A write-up from the 2018-19 school year is here.

A skydiver jumps from a plane. How fast is he or she going at any time? There is a fairly simple expression for the drag on a body falling in air (“body” as a generic in the physics sense, not meaning “dead body!”). One can insert it into a simple differential equation that is “straightforward” to solve by separation of variables; along the way, I prove some useful relations. I also show how far off is the prediction of a simpler form often given for its simpler math.