What exactly is the difference, then? Or, more appropiately, how do you meaure one without measuring the other? Gravity is a force. Acceleration is a result of force. Acceleration may be caused by gravity or some other force, or some combination. Implicit to the definition of both is the concept of mass. You cannot have gravity or acceleration without mass. Therefore we measure both gravity (the force), and acceleration (the result of force over time) using mass. I can see that since acceleration involves the variable time it may be possible to differentiate between the two, at least on paper. How does one measure either acceleration or gravity without involving the other? Or can you point me to research where the difference has been measured? I'm very interested in this, it has some implications for work I am involved in. -Adam On 8/31/05, Herbert Graf wrote: > On Wed, 2005-08-31 at 11:22 -0400, William Couture wrote: > > On 8/31/05, Gus Salavatore Calabrese wrote: > > > > > > I see no way to differentiate between braking and going downhill. Any > > > ideas ? > > > > None whatsoever. This is the basis of Einstein's General Theory of > > Relativity. > > Yes, there is a difference, it's just really hard to measure. > > Force due to acceleration is constant along the direction of the > acceleration. > > Force due to gravity changes dependant on the distance between the two > objects. > > In most cases the difference is too small to measure, but that doesn't > change the fact that there IS a difference, and it CAN (and has) been > measured. -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist