A lunar month is about 28 days. If the Moon were closer to Earth than it now is, the lunar month would be
1) less than 28 days,
2) more than 28 days,
3) still 28 days,
mainly because
4) centripetal force would lessen with decreased distance.
5) a closer Moon means an increase in both gravitational force and speed, which in a smaller orbit means shorter time.
6) orbital speed about the center of mass of Earth-Moon system is not dependent upon the distance between Earth and Moon.
7) of tidal friction.
Question 2
A 400-N person stands on the surface of Earth. If he were somehow able to stand on a ladder so that he was twice as far from the center of Earth, he would weigh
1) 0 N.
2) 100 N.
3) 200 N.
4) 400 N.
This would be because
5) he would be above the atmosphere.
6) his mass would be the same wherever he was.
7) the force due to gravity obeys the inverse square law.
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