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oscillations test question



I'm interested in hearing what folks think of the following question
in the test bank for Giancoli:

Chap 14 #11. Two hundred grams hung on a spring stretches it 8.4 cm.
How much energy is stored when stretched 8.4 cm?

Before reading the rest, decide how you would answer this and why.

While a number of answers are possible, the most reasonable answer in
my mind is zero. By definition, a system at rest in stable
equilibrium is at a potential minimum.

The purported answer of 82 mJ only considers the increase in the
elastic potential energy and neglects the decrease in the
gravitational potential energy.

It is true that no zero points are specified. This is why I can only
say my answer is reasonable, and other interpretations are possible.
Comments?
--
Carl E. Mungan, Asst. Prof. of Physics 410-293-6680 (O) -3729 (F)
U.S. Naval Academy, Stop 9C, Annapolis, MD 21402-5026
mungan@usna.edu http://physics.usna.edu/physics/faculty/mungan/

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