W

W

atomic symbol for tungsten

weigh

1. to measure the mass or weight of, as in “to weigh a sample”
2. to have a weight of, as in “to weigh 100 N”

weight (of a body)

1. in a particular reference frame, the product of the mass of a body and the local acceleration of free fall

Note: The acceleration of free fall on the Earth is affected by both the acceleration due to gravity and the Earth’s rotation.

2. in commercial usage as well as much everyday usage (and even in a few common laboratory terms such as wet weight, dry weight, and ash weight), the mass of a body

Welch-Satterthwaite formula

the following mathematical monstrosity, which is used (in some situations) to calculate the effective degrees of freedom (ν_eff) for a combined standard uncertainty:

νeff

=

uc4(y) N ∑ i = 1   ui4(y) νi

Given ν_eff and a specified probability, p, one can choose a coverage factor, k_p, such that the expanded uncertainty, U_p = k_p u_c(y), provides an uncertainty interval about y with a coverage probability approximately equal to p.

wet weight; wet mass

mass of material before any drying or ashing (cf. ash weight and dry weight)

wipe

swipe