My students and I (Honors College Prep.) were having a discussion of mass...
and the qualities of inertial mass vs. gravitational mass. And then came
the question I feared, because I could not rationalize an answer, even
having spent some time looking back at my college Mechanics textbook.
Why is inertial mass always equal to gravitational mass?
My students were keen on the fact that mass and weight were not synonymous,
but nevertheless related. Weight is how hard earth pulls on an object,
which can be readily measured using a spring scale. Graphing weights of
objects vs. their mass will readily yield (small) g as the slope.
However, one can also use an inertial balance (measuring period as a
function of mass) to find the mass of an unknown, given the mass of a known
and its period.
Students understand a relationship HAS to exist; and yet, what is the
rationale?
I would be most appreciative for a response. Please forgive my ignorance if
this query sounds trivial.
-nate.
--
Nathaniel Wayne Davis
Physics Teacher
Mountain View High School
haphaestus@earthlink.net