How to start an artificial gravity? I understand how artificial gravity in space stations works. It is by normal force the wall exerts on the foot. 
But I wonder how to start it in the first place. I just learned about centrifugation in a centrifuge. To start, the side-wall of the tube produce a tangential acceleration. Because of the inertia (tendency to go tangentially) of the material contained, normal force is thus needed to keep the material from going through the tube and keep it rotating in a circle. 
But in the space station, there is no friction, so there is no way to create that tendency that produces the need for normal force in the first place. 
 A: You are quite correct that if you have items floating freely inside your space station they won't experience any artifical gravity as the station starts spinning. The artificial gravitational acceleration of an object is a consequence of its tangential velocity $v$ and is given by:
$$ g = \frac{v^2}{r} $$
where $r$ is the distance to the axis. The freely floating objects will initially have $v = 0$ and therefore $g = 0$.
As several comments have said, when you start spinning the station the air inside will start spinning as well, and that will produce aerodynamic forces on the floating objects that will eventually propel them towards the outer wall of the space station.
But assuming we're talking about the real world, you don't leave things floating about in your space station especially if you're applying any forces to it. You'd secure everything to the station walls, so everything in the station would start spinning along with the station.
A: An astronaut dressed in a magnetic suit inside a room or environment of copper or similar element in characteristics of conductivity or alloy (copper chamber) is a human magnet (magnet man) than will face a force that is opposed to his displacement inside the "chamber". If one of six sides or of all the sides than compose the chamber, one of the sides is the based side, or floor than determines the position of contact of the feet and if this side is an ferromagnétic material that attracts the astronaut at time the isstronaut is subject to an attractive force towards "below" and a force (effect Lenz) forces him to develop a work "to "ascend" or to move inside the chamber and if the magnetic suit (magnetic vinyl or similar material) has major magnetism proportionally when it  moves away from the feet, this is, the magnet is much stronger in them, shoulders and head, in a such way that the attraction towards "below" is similar in both ends and is distributed proportionally along the suit. Then we have a chamber of copper where the magnet man is attracted towards the base and it is difficult to him to displace, which looks like enough the gravity.
