Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] A question about the Earth's gravity



But the question is about the Earth's gravity. Properly that is the force
that the Earth exerts on the body. Now the weight has been interpreted in
various ways. The quoted values of g are the local gravitational
acceleration, and NOT the gravitational force. Unfortunately this
distinction is not often made.

This question of the definition of "weight" has been around many times and
has never been resolved. But the term "gravity", which should not be used
as a noun, has pretty much always been interpreted to mean the force exerted
by mass of one object on the mass of the other object. So if you define
weight as what is measured by a spring scale, then rotational effects need
to be considered. But that is a combination of effects and not purely
gravity.

Students often have a misconception that if the Earth stopped rotating that
the gravitational force will go away. So we must separate out the effects
properly.

John M. Clement
Houston, TX


The 'official' definition of g DOES include the centrifugal effect.
Physics teachers saying otherwise does not change this.

(and I believe that the 'somewhat' does indeed apply to SMALL
effects ;-)


On May 7, 2009, at May 7(Thu) 9:58 , John Clement wrote:

So the gravitational force is changed by the rotation of the
Earth? Very
interesting!!!

John M. Clement
Houston, TX


Its only somewhat above the level of AP-C if centrifugal effects are
deemed somewhat above the level AP-C

_________________________

Joel Rauber, Ph.D
Professor and Acting Head of Physics
Department of Physics
South Dakota State University
Brookings, SD 57007
Joel.Rauber@sdstate.edu
605.688.5428


We claim that the earth's gravity at its poles is slightly
greater than
that at its equator. However, I feel justification for it is not
trivial but somewhat above the level of even AP Physics C; it will
require quite a bit of calculus! Would you agree?

~ Hasan Fakhruddin
Instructor of Physics
The Idiana Academy for Science, Mathematics, and Humanities
BallState University
Muncie, IN 47306

_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l

_______________________________________________
Forum for Physics Educators
Phys-l@carnot.physics.buffalo.edu
https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l