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Thus, for example, the CGS unit of pressure, barye, is related to the CGS base units of length, mass, and time in the same way as the SI unit of pressure, pascal, is related to the SI base units of length, mass, and time: 1 unit of pressure = 1 unit of force / (1 unit of length) 2 = 1 unit of mass / (1 unit of length × (1 unit of time) 2)
One difference between the Gaussian and SI systems is in the factor 4π in various formulas that relate the quantities that they define. With SI electromagnetic units, called rationalized, [3] [4] Maxwell's equations have no explicit factors of 4π in the formulae, whereas the inverse-square force laws – Coulomb's law and the Biot–Savart law – do have a factor of 4π attached to the r 2.
One may apply any unit one pleases to the proportionality constant. If one applies the unit s 2 /lb to it, then the foot becomes a unit of force. In a four-unit system (English engineering units), the pound and the pound-force are distinct base units, and the proportionality constant has the unit lbf⋅s 2 /(lb⋅ft). [12] [13]
In the International System of Units (SI), the unit of measurement of momentum is the kilogram metre per second (kg⋅m/s), which is dimensionally equivalent to the newton-second. Newton's second law of motion states that the rate of change of a body's momentum is
Forms of matter that are not composed of molecules and are organized by different forces can also be considered different states of matter. Superfluids (like Fermionic condensate) and the quark–gluon plasma are examples. In a chemical equation, the state of matter of the chemicals may be shown as (s) for solid, (l) for liquid, and (g) for gas.
Typical dipole moments for simple diatomic molecules are in the range of 0 to 11 D. Molecules with symmetry point groups or containing inversion symmetry will not have a permanent dipole moment, while highly ionic molecular species have a very large dipole moment, e.g. gas-phase potassium bromide, KBr, with a dipole moment of 10.41 D. [3] A proton and an electron 1 Å apart have a dipole ...
Polarizability has the SI units of C·m 2 ·V −1 = A 2 ·s 4 ·kg −1 while its cgs unit is cm 3. Usually it is expressed in cgs units as a so-called polarizability volume, sometimes expressed in Å 3 = 10 −24 cm 3. One can convert from SI units to cgs units (′) as follows:
The statcoulomb (statC), franklin (Fr), or electrostatic unit of charge (esu) is the unit of measurement for electrical charge used in the centimetre–gram–second electrostatic units variant (CGS-ESU) and Gaussian systems of units. In terms of the Gaussian base units, it is