The cohesive forces between the molecules in solids are strong so they are packed closely together. This is why solids have a defined volume and shape. When a solid is heated, if enough heat is added, the molecules will gain kinetic energy and change into a liquid. Temperature can also affect solid metals by changing their conductivity, volume, magnetism, or crystalline structure. Solids are subject to many different types of stresses. Tension, compression, and bending stress are normal stresses. Shear stress and twisting stress occur when the external forces act parallel to the object’s surface. Strain is the deformation or displacement of the object that results from stress, and the way a solid reacts to stress is summarized in a stress-strain curve. This curve indicates the stiffness, elasticity, strength, and overall toughness of a substance.
