The angular momentum about the center of the planet and the total mechanical energy will be conserved regardless of whether the object moves from small r to large r (like a rocket being launched) or from large r to small r (like a comet approaching the earth).
o true o false

True

Explanation:

The angular momentum around the center of the planet and the total mechanical energy will be preserved irrespective of whether the object moves from large R  to small R. But on the other hand the kinetic energy of the planet will not be conserved because it can change from kinetic energy to potential energy.

Therefore the given statement is True.

no. dot product   =0 when vecs at right angles

i think the answer is a, hope this : )