Wavenumber Wavenumber In the physical sciences, the wavenumber (also wave number or repetency) is the spatial frequency of a wave, measured in cycles per unit distance or radians per unit distance. Whereas temporal frequency can be thought of as the number of waves per unit time, wavenumber is the number of waves per unit distance. In multidimensional systems, the wavenumber is the magnitude of the wave vector. The space of wave vectors is called reciprocal space. Wave numbers and wave vectors play an essential role in optics and the physics of wave scattering, such as X-ray diffraction, neutron diffraction, and elementary
Pound per hour not enough to sustain flight. Pound per hour Pound per hour is a mass flow unit. It is abbreviated as PPH or more conventionally as lb/h. Fuel flow for engines is usually expressed using this unit. It is particularly useful when dealing with gases or liquids, as volume flow varies more with temperature and pressure. In the US utility industry, steam and water flows throughout turbine cycles are typically expressed in PPH, while in Europe these mass flows are usually expressed in metric tonnes per hour: Minimum fuel intake on a jumbo jet can be as low as 150 lb/h