Watch What You Say

Watch What You Say

Watch What You Say

A scientist purchased an expensive watch in 1939 that he utilized in his experiments. He conducted his experiments for a month at Pike’s Peak. He returned to the shop where he purchased his watch. Which is the more likely statement that he made to the shopkeeper and why?

a. The watch was erratic running slow on ascent and fast on descent. I was thoroughly displeased.

b. The watch ran slow and it ruined my experiment.

c. The watch ran fast and I’m very disappointed.

d. The watch lived up to my expectations. I’ll recommend it to my colleagues.

The answer is:

In a vacuum, the moment of inertia of the flywheel is slightly decreased over its amount at sea level (an altitude approximating the level at which the watch was manufactured). At sea level the viscosity of the air adds to the moment of inertia of the flywheel. The flywheel experiences the drag of this air. Since this error is compensated for at sea level, the watch will run faster at altitudes where the viscosity of the air is less and offers less resistance to the flywheel.