Everyday physics: the stress tensor

This is very similar to the notion of pressure, as described in the previous post on flotation. Indeed, the units of stress and the units of pressure are the same. The main difference, however, is that the stress is more directional than pressure. So in the picture of the cables above, the force is proportional to the area in the yz plane (the cross sectional area), while the force points in the x direction. However, if we though about it in the vertical direction, the cables are not that good at transmitting force in that direction, so we would expect that the force per unit area going upwards is different. This is on contrast with pressure that goes into all directions at once.