Tensile strength
The tensile strength of a material is the maximum amount of tensile stress that can be applied to it before it ceases to be elastic. If too much force is applied the material will break or become plastic, i.e., once the force exertion is stopped the material won't go back to its initial shape.Tensile strength is measured in units of force per unit area. In the SI system, the unit is newton per square metre (N/m²). The U.S customary unit is pounds per square inch (psi).
The breaking strength of a rope is specified in units of force, such as newtons, without specifying the cross-sectional area of the rope. This is often loosely called tensile strength, but this not a strictly correct use of the term.
The ultimate tensile strength (UTS) of a material is the force per unit area at which it breaks in two.
Tensile strength can be measured for liquids as well as solids. For example, when a tree draws water from its roots to its upper leaves by transpiration, the column of water is pulled upwards from the top by capillary action, and this force is transmitted down the column by its tensile strength. Air pressure from below also plays a small part in a tree's ability to draw up water, but this alone would only be sufficient to push the column of water to a height of about ten metres, and trees can grow much higher than that. (See also cavitation, which can be thought of as the consequence of water being "pulled too hard".)
