NASA-Systems Engineering

# The hectare ha is a special name for the square

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Unformatted text preview: ce of a closed circuit in which an electromotive force of one volt is produced when the electric current in the circuit varies uniformly at a rate of one ampere per second. hertz (Hz = 1/s) The hertz is the frequency of a periodic phenomenon of which the period is one second. joule (J = N.m) The joule is the work done when the point of application of a force of one newton is displaced a distance of one meter in the direction of the force. lumen (lm = cd.sr) The lumen is the luminous flux emitted in a solid angle of one steradian by a point source having a uniform intensity of one candela. radian (rad) The radian is the plane angle between two radii of a circle that cut off on the circumference an arc equal in length to the radius. lux (lx = lm/m2) The lux is the illuminance produced by a luminous flux of one lumen uniformly distributed over a surface of one square meter. steradian (sr) The steradian is the solid angle that, having its vertex in the center of a sphere, cuts off an area of the surface of the sphere equal to that of a square with sides of length equal to the radius of the sphere. newton (N = kg .m/s2) The newton is that force which, when applied to a body having a mass of one kilogram, gives it an acceleration of one meter per second squared. C.2.4 ohm (Ω = V/A) The ohm is the electric resistance between two points of a conductor when a constant difference of potential of one volt, applied between these two points, produces in this conductor a current of one ampere, this conductor not being the source of any electromotive force. Derived SI Units with Special Names In addition to the units defined in this subsection, many quantities are measured in terms of derived units which do not have special names—such as velocity in m/s, electric field strength in V/m, entropy in J/K. becquerel (Bq = 1/s) The becquerel is the activity of a radionuclide decaying at the rate of one spontaneous nuclear transition per second. degree Celsius (°C = K) The degree Celsius is equal to the kelvin and is used in...
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## This document was uploaded on 02/26/2014 for the course E 515 at University of Louisiana at Lafayette.

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