These are good questions. The short answer to all of them is, "it depends on your frame of reference."
Acuben said:
If you are holding a charged object in your hand and you spin your hand in circular motion. Is there a current?
According to you, no, because you are stationary in your own reference frame. But according to a person in a reference frame in which you appear to be rotating, yes, there is a current.
Acuben said:
also...
If you setup a simple circuit with a DC in shape of a circuit.
I don't know what you meant here, but ok. So you have a DC circuit. EDIT: Oh, I think you meant to say that the circuit was in the shape of a circle. Gotcha.
Acuben said:
Let's say the current is towards clockwise direction. If you spin the whole circuit in clockwise direct at the same speed of the current, would you get double the current?
Again, according to a person for whom the circuit is spinning, yes, the charges have an extra component to their motion.
Acuben said:
Or if you force it to spin at the opposite direction same speed of the current, then would you get 0 current?
Also possible. An interesting consequence of the fact that some observers see charges as being stationary while others see those same charges as being in motion is that the latter will claim that there are magnetic fields present, whereas the former will see only electric fields. At the end of the day, everyone has to agree on the observed
effects of whatever fields are present, they just might not agree upon the
causes. This idea suggests that electricity and magnetism are just two aspects of the same phenomenon, which has come to be called electromagnetism. This sort of "coincidence", that although observers in relative motion may disagree about what physics is causing certain effects, the effects themselves don't differ, was the also one of the major inspirations for Einstein's Special Theory of Relativity.
Acuben said:
Or do I have the concept of current completely wrong?
(current is charges per second)
No, I think that you are conceptualizing things just fine.
Acuben said:
oh and...I have no idea how fast electrons can move in a circuit
That's yet another interesting question. Although individual electrons in a conductor can move quite fast (with the average speed depending on temperature), their velocities tend to be in all different directions (i.e. the velocities are distributed randomly), because the electrons tend to keep colliding with other particles over and over again. As a result, under normal circumstances, these velocity directions all tend to average out and there is no NET motion in any given direction. However, if an electric field is applied across the conductor (as is the case in an electric circuit), then the electrons, although their individual velocities will still rapidly change direction due to collisions, will tend to migrate overall in the direction opposite to that of the applied electric field. So, on top of the individual electron velocities, there is an overall
net motion of the charges (their velocities don't all average out to zero in this case). The velocity of the net motion is known as the
drift velocity. As you can imagine, constantly bouncing around and hitting things is a very inefficient way to get anywhere, and as a result, drift velocities tend to be very very slow -- like I mean on the order of a few
centimetres per second. Therefore, it is quite feasible to "cancel out" this net component of the charge motion by "boosting" (to use the physics jargon) to a moving reference frame.
