🚀 go-pugleaf

Regarding the mass of air demos, I like the following.  I get a weather
balloon  (I believe that Edmunds has them) and fill it with air in the
shop below the gym.  I then take it up the stairs ( a tight squeeze- and
I have inflated it to only 4 ft., 1/2 the allowed diamater!).  I then tie
a string TIGHTLY on the end and have students try to yank it- not too
hard, since the string pulls away, but hard enough to see that it is not
so easy to ACCELERATE this mass of air.  Then they love to bounce it
around the gym until it breaks.  It usually takes 2 or 3 of these to make
the point, but it is a good one.  Incidentally, do the calculations and
you find that the mass of the air is over 1 kg. In fact closer to 2, as I
recall (typing from home but the calcs are at school).  I could dig that
last piece of info out if anyone is interested.  <<Joe>>

               +-+-+-+-+-+-+-+-+-+-+-+
             Joseph F. McLaughlin, Physics
   Brentwood High School,  Brentwood (Pittsburgh), PA
johnmcl+@pitt.edu (Pitt got it wrong- it's Joe, not John!)
           (formerly jxm39@psuvm.psu.edu)