(1)
A satellite in circular orbit has a constant gravity force on
it. This force is always at right angles to the motion of
satellite, so it can't change the speed. You need a force in the
direction of motion to change the speed.
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(2) Gravity supplies the necessary centripetal
force to hold a satellite in orbit about the earth.
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(3)
A geosynchronous satellite orbits above the equator. Singapore
is on equator, but the other cities are not.
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(4) True, because of the distances involved at
higher and higher altitudes
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(5)
(a) Scientists (b) Kepler
(c) Kepler
