It is a riddle.
It is the strongest force,
to resist your force,
and yet it is not a force.
It never accelerates,
but it is always moving.
It never rests, and
it never gets tired.
It has been defined many ways,
but no one can quite capture it.
What is it?
If it refers to speed, then what is your argument about the speed of the spinning of this earth.
The earth is spinning in such a low pace, ie. 0.25 degree per minute. Does it speed up? No, the speed is constant.
When you speak about velocity, the velocity can be zero. No movement at all.
In Mathematics, when you touch on the topic on acceleration, the formula links up to velocity. Again the speed. You hold an object in the air. You drop it, still its speed.