Scientific constants and elements

The scientific constants package gives you quick access to information about scientific constants. We will look at one constant and the same will apply to all others.

Scientific Constants

[> # The default system is SI, so the option is not needed
[> SciConG := ScientificConstants['Constant']( 'G', 'system' = 'SI' ):
[> evalf( SciConG );

$6.67408 \times 10^{-11}$

[> ScientificConstants['GetError']( SciConG );

$3.1 \times 10^{-15}$

[> ScientificConstants['GetUnit']( SciConG );

$\frac{\textrm{m}^3}{\textrm{kg} \textrm{s}^2}$

[> ScientificConstants['GetUnit']( SciConG );

You can use these constants inside an equation and then evaluate them to floating-point numbers when necessary:

[> with( ScientificConstants ):
[> Force := Constant( 'G' )*Constant( 'M[Earth]' )*Constant( 'M[Sun]' )/r^2;

$\frac{\textit{Constant}(G)\textit{Constant}(M_\textit{Sun})\textit{Constant}(M_\textit{Earth})}{r^2}$

[> evalf( eval( Force, r = 152.1e9 ) ); # Force at aphelion

$3.428622513 \times 10^{22}$

[> evalf( eval( Force, r = 147.1e9 ) ); # Force at perihelion

$3.665664850 \times 10^{22}$

Here are only some of the more common units you may use, and you may refer to them either by the name or the symbol:

`speed_of_light_in_vacuum`	`c`
`permeability_of_vacuum`	`mu[0]`
`permittivity_of_vacuum`	`epsilon[0]`
`characteristic_impedance_of_vacuum`	`Z[0]`
`Newtonian_constant_of_gravitation`	`G`
`Planck_constant`	`h`
`Planck_constant_over_2pi`	`hbar`
`Planck_mass`	`m[P]`
`Planck_length`	`l[P]`
`Planck_time`	`t[P]`
`elementary_charge`	`e`
`magnetic_flux_quantum`	`Phi[0]`

To see all of them, enter

[> ?Initial_Physical_Constants

Units

All of the above constants have SI units. You can change this by adding the option 'system' = 'SystemName' where the system name is one of 'Atomic', 'CGS', 'EMU', 'ESU', 'FPS', 'MKS', 'MTS' or 'SI'.