Here are some of the ways in which we have idealized the problem:
- We are assuming that the earth is a perfect sphere, so that a cross
section through the center is a perfect circle as diagrammed. This is a
simplification since the radius of the earth varies from the equator to the
- We are assuming that the surface of the earth-at least the part where
the swimmer is located-is perfectly uniform. Actually, this isn't an
unreasonable assumption, since the surface of a large body of water tends to be
uniform. Furthermore, the problem statement specifies that it is a calm day
with no waves.
- We are ignoring the effects of tides, which would raise and lower the
surface of the sound relative to the center of the earth and the summit of
Return to lesson.
Joseph L. Zachary
Department of Computer Science
University of Utah