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Re: test problem

On Tue, 4 Dec 2001, Justin Parke wrote:

...
Use conservation of energy to find the speed of the mass as it
passes through the midpoint (i.e. 12.5 cm from the origin)"

I get the same answer that you do (2.6 m/s), but I think that the
use of the word "midpoint" is highly misleading. The midpoint of
the oscillation (assuming that it somehow remains purely vertical,
which would be very unlikely) is 20 cm from the origin--i.e., the
equilibrium position. At *that* position the speed of the mass
will be 2.8 m/s. The real problem, however, is that for the
oscillation to continue, the spring and mass will need to be
constrained against "sproinging out" as the mass continues upward
and compresses the spring by 15 cm.

John Mallinckrodt mailto:ajm@csupomona.edu
Cal Poly Pomona http://www.csupomona.edu/~ajm