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Galileo's Pendulum

What is weight?

8 Jul 2013, 14:44 UTC
What is weight?
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There then occurred to me the “glückischste Gedanke meins Lebens,” the happiest thought of my life, in the following form. The gravitational field has only a relative existence . . . . Because for an observer falling freely from the roof of a house there exists — at least in his immediate surroundings — no gravitational field.
– Albert Einstein, as quoted by Abraham Pais

Canadian astronaut Chris Hadfield aboard the International Space Station (ISS), demonstrating weightlessness with tomatoes. [Credit: International Business Times]Weight is not the same thing as the gravitational force. You don’t need a formal study of physics to know that: all you have to do is ride a swing at a playground, or drive over the lip of a hill a little too fast, or ride an elevator on a tall building. In all of these cases, you experience fluctuations in your weight: heavier at the bottom of the swing’s arc, lighter at the top, maybe even momentarily weightless. The elevator is the best example of these, since you could take a scale onto it and see how your weight changes during the various stages of acceleration. (Try it at the Sears Tower or Empire State sometime. ...

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