Skip to main content

Motion (What Unschoolers Do Intead of School)

Three year-old No. Three loves motion.  My walks with her through the neighborhood and around town are always spiked with Three’s discovery of new objects and her new uses for them.  Three was the first to discover that bicycle racks in our town aren’t actually for bicycles, they’re one bar monkey bars, also known as monkey bar.  When she was two, she noticed one day that she could see through to the other side of a bike rack.  Five seconds later, she was holding onto it with two hands, swinging back and forth with her feet lifted off the ground.  One of our fancier neighborhoods who seemed to have figured out this trick, robbed the world of the joy by placing decorative metal work across the opening.  The first time Three found one of these, I realized that two year-olds are capable of looks of the purest, un-mollified disdain. 

It should have been no surprise to me when a few weeks later, Three went from a vertical swing to a horizontal one.  Arriving at the playground one afternoon, I found Three perched on a piece of equipment made for spinning.  We call them—perhaps unoriginally—spinners.   Typically kids stand on it, push themselves off a little bit, pull the leg they pushed with up, and spin for a bit.  It’s a merry-go-round for one.  As I walked over to the bench where my partner was seated, she said, “Watch this,” and nodded at Three.

Three took hold of the handle on top of the spinner with both feet squarely on the ground, not on the little circular platform most kids stand on to enjoy the spin.  “That’s odd,” I thought. 

Then, she started running in circles as fast as she could with the handle still in her hand.  She was spinning up the platform.  As she hit critical speed, she jumped up, and threw both feet away from the center of the spinner.  With the resulting centripetal force, her body swung out making a horizontal line—from head to toe—parallel with the pavement below.  She was virtually flying.  At one point, she brought her other hand down to the standing platform making a sideways T with her arms and body.

Three continues to find new ways to move every day—much to my partner's chagrin, Three recently discovered she could pull a similar ‘spinner’ trick when buses in town go ‘round corners.)

Her exploration of motion is an innate quality of Three’s.  She has no fear, and surrenders her body to whatever she’s decided to try next.  Thanks to San Francisco’s primo weather, and her free unschooling schedule, she’s outside almost all the time.  New opportunities abound at every step!


Popular posts from this blog

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems, there seem to be fewer explanations of the procedure for deriving the conversion, so here goes!

What do we actually want?

To convert the Cartesian nabla

to the nabla for another coordinate system, say… cylindrical coordinates.

What we’ll need:

1. The Cartesian Nabla:

2. A set of equations relating the Cartesian coordinates to cylindrical coordinates:

3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system:

How to do it:

Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables.

The chain rule can be used to convert a differential operator in terms of one variable into a series of differential operators in terms of othe…

Lost Phone

We were incredibly lucky to have both been in university settings when our kids were born.  When No. 1 arrived, we were both still grad students.  Not long after No. 2 arrived, (about 10 days to be exact), mom-person defended her dissertation and gained the appellation prependage Dr. 

While there are lots of perks attendant to grad school, not the least of them phenomenal health insurance, that’s not the one that’s come to mind for me just now.  The one I’m most grateful for at the moment with respect to our kids was the opportunities for sheer independence.  Most days, we’d meet for lunch on the quad of whatever university we were hanging out at at the time, (physics research requires a bit of travel), to eat lunch.  During those lunches, the kids could crawl, toddle, or jog off into the distance.  There were no roads, and therefore no cars.  And, I realize now with a certain wistful bliss I had no knowledge of at the time, there were also very few people at hand that new what a baby…

Lab Book 2014_07_10 More NaI Characterization

Summary: Much more plunking around with the NaI detector and sources today.  A Pb shield was built to eliminate cosmic ray muons as well as potassium 40 radiation from the concreted building.  The spectra are much cleaner, but still don't have the count rates or distinctive peaks that are expected.
New to the experiment?  Scroll to the bottom to see background and get caught up.
Lab Book Threshold for the QVT is currently set at -1.49 volts.  Remember to divide this by 100 to get the actual threshold voltage. A new spectrum recording the lines of all three sources, Cs 137, Co 60, and Sr 90, was started at approximately 10:55. Took data for about an hour.
Started the Cs 137 only spectrum at about 11:55 AM

Here’s the no-source background from yesterday
In comparison, here’s the 3 source spectrum from this morning.

The three source spectrum shows peak structure not exhibited by the background alone. I forgot to take scope pictures of the Cs137 run. I do however, have the printout, and…