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Sv. ≡ 1 J/kg [44] = 1 Sv = 1 J/kg = 1 m 2 ⋅s 2. Although the definitions for sievert (Sv) and gray (Gy) would seem to indicate that they measure the same quantities, this is not the case. The effect of receiving a certain dose of radiation (given as Gy) is variable and depends on many factors, thus a new unit was needed to denote the ...
Conversion of units is the conversion of the unit of measurement in which a quantity is expressed, typically through a multiplicative conversion factor that changes the unit without changing the quantity. This is also often loosely taken to include replacement of a quantity with a corresponding quantity that describes the same physical property ...
where n > 1 is an integer and p, q, r are prime numbers, then 2 n × p × q and 2 n × r are a pair of amicable numbers. This formula gives the pairs (220, 284) for n = 2, (17296, 18416) for n = 4, and (9363584, 9437056) for n = 7, but no other such pairs are known. Numbers of the form 3 × 2 n − 1 are known as Thabit numbers.
m is a divisor of n (also called m divides n, or n is divisible by m) if all prime factors of m have at least the same multiplicity in n. The divisors of n are all products of some or all prime factors of n (including the empty product 1 of no prime factors). The number of divisors can be computed by increasing all multiplicities by 1 and then ...
The primes of the form 2n+1 are the odd primes, including all primes other than 2. Some sequences have alternate names: 4n+1 are Pythagorean primes, 4n+3 are the integer Gaussian primes, and 6n+5 are the Eisenstein primes (with 2 omitted). The classes 10n+d (d = 1, 3, 7, 9) are primes ending in the decimal digit d.
Every positive integer greater than 1 is either the product of two or more integer factors greater than 1, in which case it is called a composite number, or it is not, in which case it is called a prime number. For example, 15 is a composite number because 15 = 3 · 5, but 7 is a prime number because it cannot be decomposed in this way.
Section 3.8 introduces atomic units and gives a table of atomic units of various physical quantities and the conversion factor to the SI units. Section 7.3(v) gives a concise but clear tutorial on practical use of atomic units, in particular how to understand equations "written in atomic units".
The gal (Gal) is a unit of acceleration equal to 1 cm/s 2. [3] The dyne (dyn) is a unit of force equal to 1 g⋅cm⋅s −2 (10 μN). [3] The barye (Ba) is a unit of pressure equal to 1 dyn⋅cm −2 (100 mPa). The erg (erg) is a unit of energy equal to 1 dyn⋅cm (100 nJ). [3] The poise (P) is a unit of dynamic viscosity equal to 1 Ba⋅s (100 ...