Cold working produces the following effects

$$1.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Stress are set up in the material
$$2.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Grain structure get distorted
$$3.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Strength and hardness of the metal are decreased
$$4.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Surface finish is reduced

In a single pass flat rolling operation, a $$400mm$$ wide steel strip having a thickness of $$10mm$$ is reduced to $$8mm$$ by using a roll of $$600mm$$ diameter.

The roll-strip contact length is

In a single pass flat rolling operation, a $$400$$ $$mm$$ wide steel strip having a thickness of $$10mm$$ is reduced to $$8$$ $$mm$$ by using a roll of $$600mm$$ diameter.

Considering the situation for a maximum draft of the process, what is the coefficient of friction?