Why is the direction of pressure always perpendicular to surface area of a body for fluids ? We also assume that it is an ideal fluid here.
So , pressure acts in all directions because fluid has a tendency to flow.
Now , in book it says that for a block in water. Pressure must only act perpendicular to the surface area of block because otherwise , there is no friction between adjacent layers of the fluid. Also ,pressure must act in perpendicular direction on the sides on the tub if a block is put inside a tub which has water contained in it.
How does pressure being perpendicular does not cause that. How can we prove that pressure always act perpendicular in this way.
Also , in real life. This law must not be valid right since it only for making calculations easy? Is that true so.