Understanding Coefficient of Friction: Answers to Common Questions

[bigQ]

hello everyone. Can anyone please help with following questions?

1. Can coefficient of friction (both static and dynamic) be greater than one? What happens if it is greater than 1 ?
2. Why coefficient of kinetic friction is less than coefficient of static friction and why it decreases at higher velocities?

Thanking you in advance.

 

[Meir Achuz]

1. There is nothing magical about 1 for COF.
2. Friction is due to temporary welding of the two surfaces, which is less effective as speed increases.