Does the coefficient of kinetic friction depend on speed?

Question

and give an explanation to your answer please

Answer 1

In many contexts, you can ignore it. Like sliding blocks on tables and stuff like that.
In some contexts, it does highly depend on speed. These are the cases where the friction due to the air (or water if you're in a pool or something) cannot be ignored.

Answer 2

No it does not.
Kinetic friction is a force of friction agings the motion of the moving block.

f=uN
f -force of friction
u - coefficient of kinetic friction
N normal to the surface force generated by the weight of the block and perpendicular to the surface.

However, at the extreme, if the block is being moved too fast
1. the surface of the block the one that rides on the surface will heat up and may even burn. That would change the coefficient of friction.
or
2. The block may start to float as if on a cushion of air. That would make the coefficient of friction almost zero.

Answer 3

Note that when an object is stationary on a surface, very, very weak secondary molecular bonding occurs, which makes the object harder to move initially (it has a higher coefficient of friction, sometimes called "stiction"). After any meaningful displacement, though, the bonds are broken, and the ceofficient of friction drops to normal.

Answer 4

Friction by moving through the air depends on speed;
slip depends hardly on speed.