Breaking weight and breaking stress
A substance behaves as a perfectly elastic body up to its elastic limit. When the applied force exceeds that limit, the body does not return fully to its original condition when the force is withdrawn. The body retains some strain. If the applied force is gradually increased, a stage will come when the body breaks or snaps.
So, the minimum applied force or load for which a substance either breaks or snaps is called breaking weight or breaking load. The weight which must be hung from a rod of given cross-section or placed upon any structure in order to break it. It measures the cohesion of the material experimented upon.
The force per unit area of a body for which the body breaks is called breaking stress. It is the maximum force that can be applied to a cross-sectional area of a material in such a way that the material is unable to withstand any additional amount of stress before breaking.
Breaking stress = [Breaking weight / Area]