Richard Clark, KB7QHC wrote:
"I have a D Cell battery whose capacity is 3 W-HR, and I roll it along
the floor. Has power flowed?"

Reminds me of a point made by Tom Whitaker, a two-handed blackboard
scribe and celebrated E.E. Prof I had over 1/2 century ago. Tom wrote
with one hand and erased with the other so he would have a clear space
to write more.To drive home his definition of current, Tom spat on a
piece of chalk and chunked it with vigor the length of the auditorium
where it bounced harmlessly from the rear wall. What an arm! Some ball
club sgould have signed him.

Tom said: "That spit was charged and you`ve just seen an electric
current!

Your D-cell holds much charge and rolling the cell puts charge in
motion, So, yes, power has flowed because you transferred the ability to
do work from one site to another.

Best regards, Richard Harrison, KB5WZI