Aug 1, 2010, 1:49:11 PM8/1/10
if you look up to macroscopic level entire galaxies are in cirucular
motion,its because of this motion, the work done by system is zero and
kinetic energy remain conserved,At the same time centripetal force
required for stability is provoded by the force of
attraction(gravitational),The story is same abot an electron revolving
in circular orbit about postively charged nucleus,but the force of
electrostatics acts as centripetal force,in this case.