Vapor pressure called partial pressure. For example, air at sea level, and saturated with water vapor at 20 °C, has partial pressures of about 2.3 kPa of water, 78 kPa of nitrogen, 21 kPa of oxygen and 0.9 kPa of argon, totaling 102.2 kPa, making the basis for standard atmospheric pressure. Vapor pressure is measured in the standard units of pressure. The International System of Units (SI) recognizes pressure as a derived unit with the dimension of force per area and designates the pascal (Pa) as its standard unit. One pascal is one newton per square meter (N·m or kg·m·s). Experimental measurement
Stress–strain curve these two relationships, a relationship of σ=kεἕ can be found. However, as real stresses and strains do not occur uniaxially, considerations for multiaxial stresses must be added to this relationship to model real stresses. This stress is called the tensile stress because every part of the object is subjected to tension. The SI unit of stress is the newton per square meter, which is called the pascal. 1 pascal = 1 Pa = 1 N/m Now consider a force that is applied tangentially to an object. The ratio of the shearing force to the area A is called the shear