Motion in a straight line (non-relativistic) is F = ma, the force changes the velocity and therefore increases the energy E = 1/2mv2.

For motion in a circle, the centrifugal (centripetal if you are a purist) is F = mv2/r . Energy is = 1/2 m times tip speed squared.

i.e. energy is a function of change in force (delta force) not the centrifugal.

So an electron in free space when acted on by a force (to accelerate it) changes energy, but one circulating a nucleus in a molecule has a force but no change in energy.

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