How children swing
作者:
Stephen M. Curry,
期刊:
American Journal of Physics
(AIP Available online 1976)
卷期:
Volume 44,
issue 10
页码: 924-926
ISSN:0002-9505
年代: 1976
DOI:10.1119/1.10230
出版商: American Association of Physics Teachers
数据来源: AIP
摘要:
Everyone knows how to do it, but not everyone knows how it works. In this analysis of the motion of a playground swing, it is shown that, under conditions of constant pumping, the stored energy increases approximately exponentially with time. A comparison is made between this system and other parameteric amplifiers in various fields of physics, and the problem of starting a swing from rest is discussed.
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