Final answer:
The maximum unit stress that a material can endure without causing permanent deformation is called the breaking stress or tensile strength. The breaking stress depends on the material's properties, such as its elasticity and strength. Exceeding the breaking stress can lead to fracture of the material.
Step-by-step explanation:
The maximum unit stress that a material can endure without causing permanent deformation is called the breaking stress or tensile strength. This is the stress at which the material will start to undergo plastic deformation and will not return to its original shape and size when the load is removed. The breaking stress of a material depends on its properties, such as its elasticity and strength.
For example, different metals may have different breaking stresses. Aluminum may have a breaking stress of 2.2 × 10^8 Pa, while steel can have a breaking stress as high as 20.0 × 10^8 Pa. This means that steel can withstand much higher stress than aluminum before undergoing permanent deformation.
It is important to note that the breaking stress is a maximum limit and exceeding this stress can lead to fracture of the material.