Skip to main content

Harold Daw Inventor of the Air Table!

D.r Harold Daw
In the late 1950’s, my uncle, then a teenager, found himself at odds with the Law in Las Cruces, NM.  Simply put, the police had decided he was, in fact, his brother, wanted for fleeing a drag race in the same car my uncle had just driven home.  Despite his repeated pleas that they were arresting the wrong Carter boy, the police persevered, first handcuffing my uncle, and then shuffling him into the police car.  Unbeknownst to them, the woman who lived across the street from my dad’s family had observed everything.  Turning to her husband, she said Harold, they go the wrong boy!  You go down to the station and help them straighten this out!”  That’s how my uncle found himself riding back to his house in the car of Dr. Harold Daw, head of the New Mexico State University physics department. 


The Hot Rod in Question
The reason I bring this story up now, isn’t because of its somewhat topical nature in relation to the state of police arrests in this day and age.  (Although I do suspect prisoners can no longer be liberated on the say-so of a physics department head.)  Nope, it’s because I found an air table, at the Excelsior Science Workshop[3] this week, and well… Dr. Daw in addition to being the ‘great liberator’ of wrongly accused teens in Las Cruces, New Mexico, is also the documented inventor[1] of the air table!  Ever played air hockey?  Dr. Daw’s invention for studying two-dimensional mechanics in physics lab ultimately became best known as the air hockey table!

From AJP article [1]


Dr. Daw first publicly documented his invention in a 1963 issue of The American Journal of Physics, known colloquially to physics students the world over as the AJP.  In this article, he pointed out the advantages of the device for studying two dimensional collisions, and gave explicit instructions for how to build one. In the original implementation, they floated glass pucks on the air cushion.  In our local incarnation, the glass pucks have become CDs!

Like many-a-rock star, in 1987, Dr. Daw topped his original offering by adding... wait for it... fire!  The images in the AJP article does’t due the experience justice, but the video by +Jared Ficklin who built a fire-table of his own does!

Comments

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…

The Valentine's Day Magnetic Monopole

There's an assymetry to the form of the two Maxwell's equations shown in picture 1.  While the divergence of the electric field is proportional to the electric charge density at a given point, the divergence of the magnetic field is equal to zero.  This is typically explained in the following way.  While we know that electrons, the fundamental electric charge carriers exist, evidence seems to indicate that magnetic monopoles, the particles that would carry magnetic 'charge', either don't exist, or, the energies required to create them are so high that they are exceedingly rare.  That doesn't stop us from looking for them though!

Keeping with the theme of Fairbank[1] and his academic progeny over the semester break, today's post is about the discovery of a magnetic monopole candidate event by one of the Fairbank's graduate students, Blas Cabrera[2].  Cabrera was utilizing a loop type of magnetic monopole detector.  Its operation is in concept very simpl…

Unschooling Math Jams: Squaring Numbers in their own Base

Some of the most fun I have working on math with seven year-old No. 1 is discovering new things about math myself.  Last week, we discovered that square of any number in its own base is 100!  Pretty cool!  As usual we figured it out by talking rather than by writing things down, and as usual it was sheer happenstance that we figured it out at all.  Here’s how it went.

I've really been looking forward to working through multiplication ala binary numbers with seven year-old No. 1.  She kind of beat me to the punch though: in the last few weeks she's been learning her multiplication tables in base 10 on her own.  This became apparent when five year-old No. 2 decided he wanted to do some 'schoolwork' a few days back.

"I can sing that song... about the letters? all by myself now!"  2 meant the alphabet song.  His attitude towards academics is the ultimate in not retaining unnecessary facts, not even the name of the song :)

After 2 had worked his way through the so…