Physical Constants

This page contains some basic Physical Constants, as well as some common materials properties.
While efforts have been made to ensure the accuracy of the information the reader is cautioned to verify the information, prior to use. (Updated Feb 2009)

GENERAL CONSTANTS

Avogadro's number

Na 6.02214 x 10^23 molecules/mole
astronomical unit A.U. 1.49597870 x 10^11 m 4.90806660 x 10^11 ft
electron charge (elementary charge) e 1.60210 x 10^-19 coulombs
electron rest mass me 9.10938 x 10^-31 kg
Proton rest mass mp 1.67262 x 10^-27 kg  
Neutron rest mass mn 1.67493 x 10^-27 kg 1.068846 x 10^-9 ft^3/lb/s^2
Charge to mass ratio for electron e/me 1.75874 x 10^11 C kg^-1  
Electron radius re 2.81794 x 10^-15 m  
Quantum-charge ratio h/e 4.13586 x 10^-15 J s C^-1  
Compton wavelength of electron lambda 2.42631 x 10^-21 m  
Compton wavelength of neutron   1.31959 x 10^-15 m  
Compton wavelength of proton   1.32141 x 10^-15 m  
Rydberg constant R(infinity subtext) 1.0973731 x 10^7 m^-1m  
Muon mass   1.88353 x 10^-28 kg  
Faraday constant F 9.64853 x 10^4 C mol^-1  
ideal gas constant R 8.31447 Joules per mole degree Kelvin
Molar volume ideal gas V0 2.2414 x 10^-2 m^3 mol^-1  
Boltzmann constant k 1.38065 x 10^-23 joules per degrees kelvin  
First radiation constant c1 3.74177 x 10^-16 W m^2  
Second Radiation Constant c2 1.43878 x 10^-2 metres by degrees Kelvin  
Wien displacement constant b 2.8978 x 10^-3 metres by degrees kelvin  
Stefan-Boltzmann constant theta 5.6704 x 10^-8 W m^-1 ¡K^-4  
Thosmson cross section 8ß(re^2)/3 6.6516 x 10^-29 m^2  
Gyromagnetic ration of proton   2.67519 x 10^8 rad s^-1 T^-1  
Bohr Magneton µB 9.27401 x 10^-24 J T^-1  
Nuclear Magneton µN 5.0508 x 10^-27 J T^-1  
Proton Moment µp 1.41061 x 10^-26 J T^-1  
Electron magnetic Moment µe 9.28476 x 10^-24 J T^-1  
Neutron magnetic Moment µn 9.662364 x 10^-27 J T^-1  
Muon magnetic Moment µµ 4.490451 x 10^-26 J T^-1  
Electron-volt eV 1.60210 x 10^-19 J(eV)^-1  
Zeeman splitting constant µB/hc 4.6685 x 10 m^-1 T^-1  
Planck's constant h 6.626069 x 10^-34 Joule seconds
Fine Structure Constant alpha 7.29735 x 10^-3 J s  
Poisson's Ratio
(elastic isotropic materials)
µ 0.25
speed of light in a vacuum c 2.997925 x 10^8 m/s 9.83571056 x 10^8 ft/s
standard gravitational acceleration go 9.80665 m/s^2 32.17404856 ft/s^2
standard atmosphere atm 101325 Pa 14.6959 psi
universal gravitational constant G 6.670 x 10^-11 m^3/kg/s^2 1.068846 x 10^-9 ft^3/lb/s^2
atomic mass unit µ 1.66054 x 10^-27 kg  
Bohr radius a0 5.29177 x 10^-11 m  

Energy Associated With

Unified atomic mass unit c^2/Ne 9.31478 x 10^8 eV u^-1  
Proton Mass mp c^2 / e 9.38256 x 10^8 eV mp^-1  
Neutron mass mn c^2 / e 9.39550 eV mn^-1  
Electron mass me c^2 /e 5.11006 x 10^5 eV me^-1  
Cycle e/h 2.41804 x 10^14 Hz(eV)^-1  
Wavelength ch/e 1.23981 x 10^-6 eV m  
Wave number e/ch 8.06573 x 10^5 m^-1(eV)^-1  
¡K e/k 1.16049 x 10^4 ¡k(eV)^-1  

STATIC  (µs) AND KINETIC (µk) FRICTION COEFFICIENTS

µs µk

steel

0.4 0.3
ice 0.02 0.01
wood 0.2 0.2
plastic 0.2 0.2
clay 0.9 0.8
rubber 0.9 0.8
rock 0.4 0.3

STRUCTURAL STEEL

modulus of elasticity

Es 29000 ksi 200000 MPa
coefficient of thermal expansion c 6.5x10^-6 per °F 11.7x10^-6 per °C
Poisson's Ratio µ 0.28
Shear modulus of elasticity Gs 78000 MPa

ALUMINUM

modulus of elasticity

Ea 10150 ksi 70000 MPa
coefficient of thermal expansion c 13x10^-6 per °F 23.4x10^-6 per °C
Poisson's Ratio µ 0.33
Shear modulus of elasticity Ga 26000 MPa

CONCRETE

modulus of elasticity
(normal density concrete) 

Ec 57000(f'c)^0.5 psi 5000(f'c)^0.5 MPa
coefficient of thermal expansion c 5.7x10^-6 per °F 10.0x10^-6 per °C
Poisson's Ratio µ 0.15 to 0.2

MASONRY

modulus of elasticity

Em 1000f'm MPa
coefficient of thermal expansion c 3.4x10^-6 per °F 6.1x10^-6 per °C
shear modulus Ev 400f'm MPa

TIMBER

modulus of elasticity (varies with species)

Et 1000000 to 1930000 psi 6000 to 12500 MPa
coefficient of thermal expansion c 22x10^-6 per °F 40x10^-6 per °C

GLASS FIBER

modulus of elasticity

E 4350 ksi 30000 MPa
tensile strength t 87 ksi 600 MPa

GLASS & CARBON FIBER

modulus of elasticity

E 5365 ksi 37000 MPa
tensile strength t 87 ksi 600 MPa

CARBON FIBER

modulus of elasticity

E 14500 ksi 100000 MPa
tensile strength t 174 ksi 1200 MPa

ARAMID FIBER

modulus of elasticity

E 7830 ksi 54000 MPa
tensile strength t 189 ksi 1300 MPa