Ch.7 Part 2 Hooke's Law and Young Modulus

Hooke's Law

Extension is directly proportional to applied force until the spring reaches its elastic limit.

F = kx

Compressive

Describes a force that squeezes an object

Tensile

capable of being stretched

Stress

Force per unit cross-sectional area that acts perpendicular to the surface. (in Pascals)

Strain

Extension per unit length (no units but usually measured as a percent)

Young modulus

stress/strain

assuming limit of proportionality has not been exceeded

Strain energy

Stored energy in an object due to elastic deformation

Gradient of a stress strain graph

Young modulus

Gradient of a force-extension graph

spring constant k

Area under a force-extension graph

Elastic strain energy

Elastic Limit

The value of stress beyond which an object will not return to its original dimensions.

Elastic Deformation

An object that returns to its original length when the force is removed has deformed elastically.

Plastic Deformation

An object that does NOT return to its original length when the force is removed.

Limit of Proportionality

The point beyond which extension is no longer proportional to the force.

Springs in Series and Parallel.

Opposite of resistors (which is on formula sheet)