Re: dimensionless units & Mach Number

[Joel Rauber <Joel_Rauber@SDSTATE.EDU>]

Michael Commented:
> (3) Joel Rauber suggests using Mach number as another example of a
> dimensionless unit to help students get used to this idea.  Analogies are
> always good, but Mach number strikes me as even more obscure than radians,
> i.e. the students are not used to it.

My suggestion (never tried by me) was predicated on the idea that Mach
number might be less obscure than radians to students.  Perhaps it is
showing my age by thinking that!  When I was a kid (60's and early 70's)
most of the kids in middle school (at least the boys) had a real good idea
of Mach number.  I suspect my older siblings who were young in the 50's also
had a good idea.

Some of you high school teachers on Phys-L, what is your impression of the
state of awareness of Mach number in your students?

If it is a more obscure idea than my suggestion is for the birds.

Joel Rauber
Joel_Rauber@sdstate.edu