. A constant force, F, is applied to a block sitting on a bench. There could be other forces acting on the block at
the same time. In which of the following cases is no work done on the block by F?
a) The force is applied to the block, and it moves in the same direction as the force.
b) The force is applied to the block, and the block moves in the opposite direction of
the force.
c) The block does not move.
d) The force is applied perpendicular to the block's motion.