Any surface which is wrinkled has a larger surface area than the space it actually takes up.
smooth surface
When a rough surface like a road becomes wet, the water fills in the gaps and irregularities in the surface, smoothing it out. The smooth surface of the water reflects more light, making it appear shiny and increasing its reflectivity.
Even seemingly smooth surfaces have microscopic imperfections that make contact points rough at a very small scale. When these contact points slide against each other, the imperfections create friction and resistance, even though the surface appears smooth at a larger scale.
Smooth surface
No it does not have to be smooth.
The rough surface is better than the smooth surface for the frictional force to act.
It is not smooth it has craters
Here we are talking about the surface of the muscles..... Smooth muscles have smooth surface while striated muscles have rough surface.....
Smooth
Surface tension of water draws it into a larger drop. It will do that on any nonporous surface- metal, glass, smooth plastic, etc.
Rub the surface down with emery cloth and water. This should give you a smooth surface to work on.
smooth surface