Weight

["Rauber, Joel Phys" <RAUBERJ@mg.sdstate.edu>]

David wrote and Marlow cheered


> BTW, since gravitational forces (locally) are not "real" but are artifacts
of
> the use of a noninertial frame used to describe the physics, I prefer 
*not*
> to define the concept of "weight" as (the magnitude of) the gravitational
> force on an object.  Such a definition makes an object's weight depend on
the
> coordinate system of the observer.  I prefer to define weight as what 
others
> define as "apparent weight" which is simply the magnitude of the
> *non*gravitational force of support on a body which prevents a free fall
> state (or equivalently, which deflects the motion from a free fall state).
> This definition of weight is independent of the frame of the observer and
> agrees with our usual sensations of weight.

I too define weight in this fashion, although for simpler reasons than 
talking about non-inertial frames, and free-fall frames etc.

Simply put, if you define weight to be the gravitational force acting on an 
object; how do you explain why we say astronoughts are weigtless while 
orbiting the earth, since they still have a gravitational force acting on 
them.

Therefore defining weight as the magnitude of the non-gravitational force 
present balancing the gravitational force on the scale used, relieves one 
from the above conundrum and allows one to consistantly understand the term 
weightless up on the space-shuttle

Joel