W

watt - unit for power (1 joule of work per second)
wave front - the front of a wave
wavelength - distance between two similar points on a wave, e.g. crest to crest
weak interaction - force involved in beta decay
weight - product of mass and the acceleration due to gravity. Force of gravity on a body.
weightless - having no weight. Only true far out in deep space. Sensation in free fall.
wheatstone bridge - apparatus used for measuring resistance by comparison
whirlpool galaxy - an optical double galaxy in Canes Venatici (M51)
white dwarf - a very dense, small star. Later stage in the evolution of a star than a red giant
wig-wag - inertia balance
wimshurst machine - a type of electrostatic generator
work function - minimum energy needed for a free electron to escape from a surface