"Inertial mass" is the ratio of the net force acting on an object to its
acceleration.
"Gravitational mass" is the ratio of the gravitational force acting on
an object to the local strength of the gravitational field.
The fact these two types of mass are directly proportional to each other
is not obvious from their definitions.
If the same net force is applied to two objects and the resulting
acceleration differs, then the two objects have different inertial
masses.
If two objects are placed at the same position (at different times) in a
gravitational field and experience different gravitational forces, then
they have different gravitational masses.
The relative values of forces can be measured by observing the
distortion of a constraint, such as the elongation or compression of a
coiled spring.
The concept of "mass" can be deduced simply in simple configurations.
Once the concept is accepted as useful in simple configurations, it can
be applied in more complicated situations by analogy. The usefulness of
its application in more complicated situations is judged by the
agreement between theoretical calculations involving the use of the mass
concept and experimental measurements.
Daniel Crowe
Oklahoma School of Science and Mathematics
Ardmore Regional Center
dcrowe@sotc.org
-----Original Message-----
From: Forum for Physics Educators [mailto:PHYS-L@list1.ucc.nau.edu] On
Behalf Of Jim Green
Sent: Monday, October 18, 2004 3:43 PM
To: PHYS-L@LISTS.NAU.EDU
Subject: [PHYS-L] Mass
Can someone pleases tell me what "mass" is?
The symbol "m" is spread all over physics topics, but I don't know what
it is.
Is it the same number in every equation wherein it appears?
Mass seems to be an invention by someone at some point for some purpose
but
I don't understand the process of the development of it's usage.