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PHYSICS 231
2nd Midterm, November 13, 1995, 10:00am-11:00am
Instructor: P. Q. Hung

Do all problems (25 points each). READ them carefully. You have to EXPLAIN all your answers QUANTITATIVELY. DO NOT just write them down.

Useful formulas:

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I) A child of mass 25 kg stands at the edge of a rotating platform of mass 150 kg and radius 4.0 m. The platform with the child on it rotates with an angular speed of 6.2 rad/s. The child jumps off in a radial direction (i.e. has no tangential velocity). What happens to the angular speed of the platform? Treat the platform as a uniform disk. (Give a quantitative explanation.)

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II) Use Kepler's third law to calculate the mass of the sun, assuming that the orbit of the earth around the sun is circular, with radius tex2html_wrap_inline87 km. (Recall T= 365 days.)

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Salvatore John Dibartolo
Tue Oct 1 03:18:21 EDT 1996