Re: oscillations test question

[Robert Cohen <Robert.Cohen@PO-BOX.ESU.EDU>]

I asked:

> If the 200 grams is then stretched a distance x from the new 
> equilibrium point, the potential energy relative to the new 
> equilibrium point is equal to 1/2 kx^2.  What do you call
> the quantity 1/2 kx^2?  The difference in the elastic-
> gravitational potential energy?

to which Carl E. Mungan answered:

> I generally call it the total PE. Of course that assumes there are no
> other potential energies of interest.

I can live with that.  I just thought there was a more descriptive name
for it so that students wouldn't interpret it as the total PE for *any*
situation.

> A favorite Mazur question of mine is:
>
> "An object hangs motionless from a spring. When the object is pulled
> down, the sum of the elastic PE of the spring and the gravitational
> PE of the object and Earth:
> 1. increases
> 2. stays the same
> 3. decreases."

So, are you using the phrase "total PE" as short-hand for 
"sum of the elastic PE of the spring and the gravitational
PE of the object and Earth"?  (or "SOTEPOTSATGPOTOAE" for short)

____________________________________________
Robert Cohen; rcohen@po-box.esu.edu; 570-422-3428; http://www.esu.edu/~bbq
Physics, East Stroudsburg Univ., E. Stroudsburg, PA 18301

This posting is the position of the writer, not that of SUNY-BSC, NAU or the AAPT.