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Rotational frequency, also known as rotational speed or rate of rotation (symbols ν, lowercase Greek nu, and also n), is the frequency of rotation of an object around an axis. Its SI unit is the reciprocal seconds (s −1 ); other common units of measurement include the hertz (Hz), cycles per second (cps), and revolutions per minute (rpm).
The speed of sound is the distance travelled per unit of time by a sound wave as it propagates through an elastic medium. More simply, the speed of sound is how fast vibrations travel. At 20 °C (68 °F), the speed of sound in air, is about 343 m/s (1,125 ft/s; 1,235 km/h; 767 mph; 667 kn), or 1 km in 2.91 s or one mile in 4.69 s.
Varying their angle manages water flow, thereby regulating turbine speed and energy produced by it. A wicket gate , or guide vane , is a ring of gates (or vanes) surrounding a water turbine which control the flow of water entering it; varying the aperture between them manages the rate of the turbine's spin, and thereby the amount of electricity ...
Water is also central to acid-base neutrality and enzyme function. An acid, a hydrogen ion (H +, that is, a proton) donor, can be neutralized by a base, a proton acceptor such as a hydroxide ion (OH −) to form water. Water is considered to be neutral, with a pH (the negative log of the hydrogen ion concentration) of 7 in an ideal state.
Rotational transitions, in which the molecule gains a quantum of rotational energy. Atmospheric water vapour at ambient temperature and pressure gives rise to absorption in the far-infrared region of the spectrum, from about 200 cm −1 (50 μm) to longer wavelengths towards the microwave region.
On many kinds of disc recording media, the rotational speed of the medium under the read head is a standard given in rpm. Phonograph (gramophone) records , for example, typically rotate steadily at 16 + 2 ⁄ 3 , 33 + 1 ⁄ 3 , 45 rpm or 78 rpm (0.28, 0.55, 0.75, or 1.3, respectively, in Hz).
Water metering is the practice of measuring water use. ... whose rotation speed depends on the velocity of water flow. Multi-jets are very accurate at low flow rates ...
is the rotational radius measured in millimeters (mm), and is rotational speed measured in revolutions per minute (RPM). To avoid having to perform a mathematical calculation every time, one can find nomograms for converting RCF to rpm for a rotor of a given radius.