According to the scientific definition, which is not an example of work?

A.

pushing a tack into a block of cork

B.

pulling a nail out of a piece of wood

C.

brushing teeth

D.

leaning against a large cargo crate

The answer should be D, because there is no motion involved. Unless, of course, you are heavier than a large cargo crate.

Work is expressed in Joules, which are Newtons times meters. Meters are a unit of distance, so if the force (in Newtons) is not producing any distance, there is no work.