Friction and Elasticity (Hooke's Law)

Fs ≤ μsN
Fk = μkN
F = -kΔx
stress = F/A
strain = ΔL/L0

Fs = static friction
μs = static coefficient of friction
Fk = kinetic frction
μk = kinetic coefficient of friction
F = spring force
k = spring constant
Δx = amount of extension