"Don1" wrote in message
oups.com...
Mechanics requires only three fundamental quantity concepts: Length,
Force and Time. All of the other quantity concepts can be derived from
these three: Units of length such as inches, feet, and meters; in three
dimensions; units of force such as pounds, newtons and dynes with which
matter thrusts against other matter to displace it, and units of time
such as years, days, hours minutes and seconds during which this
happens.

Mass is a derived quantity: Being the quantity of matter in a body;
where the force exerted on and/or by it, divided by the acceleration it
causes is it's inertia; the numerical value of its quantity; in such as
slugs, kilograms or grams.

don get a new hobby