This video is an introduction to stress and strain, which are fundamental concepts that are used to describe how an object responds to externally applied loads. Stress is a measure of the distribution of internal forces that develop within a body to resist these applied loads. There are two main types of stress - normal stress, which acts perpendicular to a surface, and shear stress, which acts parallel to a surface. Strain is a measure of the displacements that occurs within a body. Again we have both normal and shear stresses. In this video I also discuss stress-strain curves, which define how stress and strain are related. Different materials have different stress-strain curves, which can be determined by performing a tensile test. The stress state at a single point within a body is actually made up components in both the normal and the shear directions. I explore this idea at the end of the video but looking at stresses obtained when we cut a bar using an inclined plane. --- The Efficient Engineer is a channel aimed at mechanical and civil engineers. The mission is to simplify engineering concepts, one video at a time! Follow me on Twitter: https://twitter.com/efficiengineer Support the channel on Patreon: https://www.patreon.com/efficientengineer