# Physics Formulae/Equations for Properties of Matter

Lead Article: Tables of Physics Formulae

## Friction

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

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

F may be any force applied to area A

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

D = dimension (length, area, volume)

$\Delta D\,\!$  = change in dimension

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

## Fluid Dynamics

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