Teach Fzx - Learning Viscosity

It started with a drinking race.  I know, it sounds like Friday night at the frat house, but this time it was a viscosity competition without inhibition-altering drugs.  Three volunteers sucked Mountain Dew, honey, or molasses through straws while their classmates cheered.

Note the cheering classmates

Mountain Dew won, of course - it always does.  Honey is slower than molasses in January, but you could tell by the look of disgust at the first taste of molasses that it's not his drink of choice.

Next was the water pistol demo.  I took the opportunity to show the wrong way to handle a firearm as the muzzle swept everybody and my finger on the trigger was making it rain. All the while I gave lip service to muzzle awareness and trigger contact.

muzzle toward students, finger on trigger - safety last

The other squirt gun was filled with motor oil and a student fired both into a sink with the proper gangsta grip.  The differences were evident in the exit stream and trigger force required.

Gansta Grip

Then on to the contrast between automatic and manual transmission oil.  Two samples of each were publicly poured from cup to cup to show the differences in drinkability.

Focus

Corn starch only costs a dollar a pound and, when mixed with water, it makes a great liquid toy that acts like a solid under stress.  My favorite is when you roll it into a ball and toss it into the air.  Between your hands it's solid but in the air it becomes a liquid again.

It's called oobleck or some such silliness

We discussed some bottles of oil that were languishing in the basement,

Manly hand lotion

and then we went to Bob is the Oil Guy for a few viscosity tables from his Motor Oil University so we could discuss the differences between motor oils and their behavior at different temperatures.

Oil Type	Thickness at 75° F	Thickness at 212° F
Straight 30	250	10
10W-30	100	10
0W-30	40	10
Straight 10	30	6

(Oil Type Varying Thickness)

bobistheoilguy.com

The problem with motor oil arises not from viscosity decrease over time, but from an increase in viscosity from age or fouling.

So I focused on basic mechanical applications of viscosity.  No aerodynamics or hydrodynamics.  No tube or pipe behavior.  No duck legs on a frozen pond.  No blood viscosity at different temperatures.  No actual viscosity measurements.  But it was a good 20 minutes - demo heavy and entertaining.  We should do more of this.