Having a smooth surface on an electric machine reduces friction and heat generation during operation. This helps improve the efficiency and performance of the machine by minimizing energy loss and wear on moving components. Additionally, a smooth surface can enhance the aesthetics of the machine and make it easier to clean and maintain.
It is on smooth surfaces because the amount of friction is less.
the tracks
The general tendency is that there is less friction on a smooth surface. The object will eventually slow down (if there are no forces to keep it moving), but the rate of slowing down will be less than on surfaces that provide more friction.
Smooth surface
Yes, that is correct. On a perfectly smooth surface, there is no friction to oppose the motion of the body, so no external force is required to keep it moving at a constant velocity. The body will continue to move in a straight line at a constant speed unless acted upon by an external force.
the tracks
Rubbing typically involves applying pressure and moving one's hand back and forth over a surface, resulting in a smooth and frictional sensation. The texture can vary depending on the surface being rubbed, such as smooth, rough, soft, or coarse.
No it does not have to be smooth.
One can learn to roller blade through practice. There are roller blade "bars" where young people in general roller blade to music which allows for a smooth surface, and all equipment is there and available. The only thing that can be negative about going to a roller rink is there is often noise from loud music, blinking lights that can be distracting to novice skaters and sometimes gets quite busy particularly on weekends and holidays.
The rough surface is better than the smooth surface for the frictional force to act.
It is not smooth it has craters