Conservation of Energy

PREFLIGHT

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Conservation of Energy

(My apologies for getting this up late, as usual, Java applets are obstreporous and took 3 hours longer than I had planned.)

Description

A pendulum of unknown mass is suspended from a platform and swings as shown in the animation (assume negligible loss of energy due to air resistance; position is shown in meters and time is in seconds).

Question

Use conservation of energy to determine the speed of the pendulum bob when it is at its lowest point. Start

3.4 m/s
0.63 m/s
1.7 m/s
Not enough info given. The pendulum mass is needed.
Other (please explain below)

honors extra

The Invention of the Year

Two years ago, in magazines like "Inc", was the rumor that someone had just invented a device that would revolutionize transportation. After a lot of hype, and investment dollars poured into this mystery invention, it turned out to be a relative of the gas-powered pogo stick (patented in 1960, marketing never got past the product liabilities. Just about everybody who used it ended up with broken bones.), only they inserted into the heels of sneakers. Using conservation of energy principles, explain just how a gas-powered pogo stick (or sneakers) could be used to commute to work.

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I received no help from anyone on this assignment.