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Re: Constraint and inertia

Leigh Palmer wrote:

Mass is the coefficient of inertia. It expresses the strength
of the tendency to "preserve velocity" quantitatively. "Mass"
has another function, its gravitational effect. Thus "inertia"
refers only to one attribute of mass. The terms are not
interchangeable in all contexts.

Was Newton aware that a "material object" has two attributes:
inertia, which appears in F=m*a, and mass, which appears in
the law of universal gravitation? Probably not. Who was the
first to make a clear distinction, and to show experimentally
that under common conditions the two physical quantities
(attributes) are identical?

In teaching we take the identity of mass and inertia for granted
when the mass of our planet is deduced from Cavendish data,
and from the value of g.