Elasticity Things to learn States of Matter Hook’s low Elasticity Stress, Strain, Elastic Moduli

Have definite volume Have definite shape Molecules are held in specific locations by electrical forces vibrate about equilibrium positions can be modeled as springs connecting molecules States of Matter Solid

Liquid Has a definite volume No definite shape Exist at a higher temperature than solids The molecules “wander” through the liquid in a random fashionThe intermolecular forces are not strong enough to keep the molecules in a fixed position

Gas Has no definite volume Has no definite shape Molecules are in constant random motion The molecules exert only weak forces on each other Average distance between molecules is large compared to the size of the molecules

An elastic material is one that returns to its original shape after a deformation. An inelastic (plastic) material is one that does not return to its original shape after a deformation. An elastic material is one that returns to its original shape after a deformation. An inelastic (plastic) material is one that does not return to its original shape after a deformation. Clay Soccer Ball

An elastic collision loses no energy. The deform-ation on collision is fully restored. In an inelastic collision, energy is lost and the deformation may be permanent.

A spring is an example of an elastic body that can be deformed by stretching. A restoring force, F, acts in the direction opposite the displacement of the oscillating body. F = -kx A restoring force, F, acts in the direction opposite the displacement of the oscillating body. F = -kx x F

When a spring is stretched, there is a restoring force that is proportional to the displacement. F = -kx F x The spring constant k is a measure of the elasticity of the spring. The spring constant k is a property of the spring The spring constant k is a measure of the elasticity of the spring. The spring constant k is a property of the spring