# Physics Formulae/Equations for Properties of Matter

Lead Article: Tables of Physics Formulae

## Friction

 Normal Force ${\displaystyle f_{n}=\mathbf {f} \cdot \mathbf {n} \,\!}$ Static Friction, lies tangent to the surface ${\displaystyle f\leqslant \mu _{s}f_{n}\,\!}$ Kinetic Friction, lies tangent to the surface ${\displaystyle f=\mu _{k}f_{n}\,\!}$ Drag Force, tangent to the path ${\displaystyle f=\mu _{d}\rho av^{2}/2\,\!}$ Terminal Velocity ${\displaystyle v_{t}={\sqrt {\frac {2fg}{\mu _{d}\rho A}}}\,\!}$ Energy dissipation due to Friction (sound, heat etc) ${\displaystyle \Delta E=f_{k}d\,\!}$

## Stress and strain

Quantity (Common Name/s) (Common) Symbol/s Definining Equation SI Units Dimension
General Stress ${\displaystyle \sigma \,\!}$  ${\displaystyle \sigma =F/A\,\!}$

F may be any force applied to area A

Pa = N m-2 [M] [T] [L]-1
General Strain ${\displaystyle \epsilon \,\!}$  ${\displaystyle \epsilon =\Delta D/D\,\!}$

D = dimension (length, area, volume)

${\displaystyle \Delta D\,\!}$  = change in dimension

dimensionless dimensionless
General Modulus of Elasticity ${\displaystyle E_{\mathrm {mod} }\,\!}$  ${\displaystyle E_{\mathrm {mod} }=\sigma /\epsilon \,\!}$  Pa = N m-2 [M] [T] [L]-1
Yield Strength/ ${\displaystyle \,\!}$
Ultimate Strength ${\displaystyle \,\!}$
Young's Modulus ${\displaystyle E,Y\,\!}$  ${\displaystyle Y={\frac {FL}{A\Delta L}}\,\!}$  Pa = N m-2 [M] [T] [L]-1
Shear Modulus ${\displaystyle G\,\!}$  ${\displaystyle G={\frac {FL}{A\Delta x}}\,\!}$  Pa = N m-2 [M] [T] [L]-1
Bulk Modulus ${\displaystyle B\,\!}$  ${\displaystyle B={\frac {P}{\Delta V/V}}\,\!}$  Pa = N m-2 [M] [T] [L]-1

## Fluid Dynamics

 density ${\displaystyle \rho =\Delta m/\Delta V\,\!}$ pressure ${\displaystyle p=\Delta F/\Delta A\,\!}$ pressure difference ${\displaystyle \Delta p=\rho g\Delta y\,\!}$ pressure at depth ${\displaystyle p=p_{0}+\rho gh\,\!}$ barometer versus manometer ${\displaystyle }$ Pascal's principle ${\displaystyle }$ Archimedes' Principle ${\displaystyle }$ buoyant force ${\displaystyle F_{b}=m_{f}g\,\!}$ gravitational force when floating ${\displaystyle F_{g}=F_{b}\,\!}$ apparent weight ${\displaystyle weight_{app}=weight-F_{b}\,\!}$ ideal fluid ${\displaystyle }$ equation of continuity ${\displaystyle R_{V}=Av=\,\!}$  constant Bernoulli's Equation ${\displaystyle p+{\frac {\rho }{2}}v^{2}+\rho gh=\,\!}$  constant