I like to ask students to consider an elevator carrying a platform balance
with an object on one platform, balanced by some calibrated "masses" on the
other. On the same elevator is an identical object being suspended
(supported) by a spring scale. Now ask questions about the effect of
varying the acceleration on the balance reading and on the spring-scale
reading.
It is of interest that the balance reading is independent of the
acceleration (unless the acceleration is the free-fall acceleration). It is
ironic that there is a sign on many balances reading "No springs, honest
weight."
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Eugene P. Mosca
Physics Department
MI350-B
United States Naval Academy
(410) 293-6668