Recent content by Sirius

I gave what you said a thought, starting with a simpler case of 2D. I realized that the same question I asked is valid for 2D too! Why 2 planes/square at a point is considered instead of one line. I am, in some sense, confusing shear stress and normal stress. I will give it some more thinking...

Thank you Sir. I had a look at the reference and the closest thing I could find is this sentence "(In physical problems we often work with quantities that require the simultaneous specification of two directions. For example, the flux of x-momentum across a unit area of surface perpendicular to...

Can you link me to a good source? I have tried many videos, websites but they all go like ' we need 3 planes to define stress at a point' or 'consider a infinitesimal cube at a point and its faces' assuming it as an axiom.

Yes, this is exactly what I want to know. Why is this so, why is one normal and two shear not enough? Thank you for the reply sir.

Equilibrium renders the matrix symmetric reducing the need for 9 to 6 dependants right? But mathematically didn't we need 9 quantities to define stress and be able to express stresses in any plane/direction? Can u please elaborate what you mean by "their directions"? I understand the principle...

My question is simple. Why do we need 9 different quantities, ie 1 normal stress and 2 shear stresses on 3 different planes, to define stress at a point? example: http://www.geosci.usyd.edu.au/users/prey/Teaching/Geol-3101/Strain/stress.html I think it should be enough to define the 3 stresses...