## All Material's Obey Hooke's Law

\[Y\]

, defined as \[Y=\frac{stress}{strain}= \frac{Force/Area}{extension/length}=\frac{F/A}{x/l}=\frac{Fl}{Ax}\]

.We can write this as

\[F=\frac{AY}{l} x\]

which has the same form as Hooke's Law.This applies when a solid material has a constant cross section along its length and is stretched to increase that length.