Answer: a) By Straight line
- According to Coulomb, the relationship between shear strength & normal stress is adequately represented by the straight line.
- In the Mohr theory, the relation between the shear strength & normal stress is not linear though shear stress depends on the normal stress.
- A definite relationship exists between the principal stress & the angle of internal friction suggested by Coulomb and Mohr.
- A straight line passes through the origin, especially for ideal pure friction material.