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newton. a unit of force in the metric system. One newton is the amount of force needed to cause a mass of
one kilogram (1,000 grams) to accelerate at a rate of one meter per second each second the force acts on it.
One newton is equal to 100,000 dynes, or 2.248 • 10-1 pound.
Newton’s first law of motion. The law of physics which describes inertia. An object at rest will try to
remain at rest, and a moving object will try to keep moving in the same direction, at the same speed, unless
it is acted upon by an outside force.
Newton’s metal. A low-melting-point metal used for the fusible links in an automatic sprinkler systems.
Newton’s metal, which is made of 50% bismuth, 31% lead, and 19% tin, melts at 95° Celsius.
Newton’s second law of motion. The law of physics concerning acceleration. The amount of acceleration
imparted to an object by a force is directly proportional to the amount of force acting on it, and inversely
proportional to the mass of the object. The greater the force, the greater the acceleration, and the greater the
mass, the less the acceleration.
Printed from Summit Aviation's Computerized Aviation Reference Library, 2/7/2007
Page 402
Newton’s third law of motion. The law of physics relating to action and reaction. For every action, there
is an equal and opposite (equal amount and opposite direction) reaction.
NFDC (National Flight Data Center) A facility in Washington, D.C., established by the FAA to operate a
central aeronautical information service for the collection, validation, and dissemination of aeronautical
data in support of the activities of government, industry, and the aviation community. The information is
published in the National Flight Data Digest.
NFDD (National Flight Data Digest). A daily publication of flight information appropriate to aeronautical
charts, aeronautical publications, Notices to Airmen, or other media serving the purpose of providing
operational flight data essential to safe and efficient aircraft operations.
nibble (data processing term). A grouping of four bits of digital data. Two nibbles form a byte (eight bits
of digital data).
nibbler. A sheet-metal-working tool. A nibbler uses a reciprocating punch to remove metal as it moves
back and forth. The punch takes away only a small bite of metal each stroke.
Nichrome. The registered trade name for an alloy of nickel and chromium. Nichrome wire, whose
resistance is about 65 times that of copper, is used for making electrical heater elements and precision
wire-wound resistors.
nickel. A silvery, hard, ductile, magnetic, metallic chemical element. Nickel’s symbol is Ni, its atomic
number is 28, and its atomic weight is 58.71. Nickel is used for plating, as an alloy in steel, and for making
batteries.
nickel-cadmium battery. A form of storage battery in which nickel hydroxide is the active element in the
positive plates, and cadmium hydroxide is the active element in the negative plates. The electrolyte is
potassium hydroxide and water.
The cells of a nickel-cadmium battery have a closed-circuit voltage of approximately 1.25 volts,
and they maintain this voltage until they are almost completely discharged. Nickel-cadmium batteries have
a low internal resistance and are ideally suited for such high-current applications as starting gas turbine
engines.
nickel silver. An alloy of copper, zinc, and nickel. Nickel silver is also called German silver.
night. 14 CFR Part 1: “The time between the end of evening civil twilight and the beginning of morning
civil twilight, as published in the American Air Almanac, converted to local time.”
nimbostratus (meteorology). A principal cloud type, gray colored and often dark. The appearance of
nimbostratus clouds is often diffused by more or less continuously falling rain or snow, which in most
cases reaches the ground. Nimbostratus clouds are normally thick enough to blot out the sun.
niobium. A silvery, soft, ductile, metallic chemical element. Niobium’s symbol is Nb, its atomic number is
41, and its atomic weight is 92.906. Niobium is used as an alloying element for steel and as a metal used in
superconductivity research.
nipple (pipe fitting). A short piece of pipe, threaded on both ends.
nitrate dope (aircraft finishing material). A finishing material whose film base is made of a cellulose
material dissolved in nitric acid. Nitrate dope has good encapsulating properties, but it is being replaced by
cellulose acetate butyrate (CAB) dope, because it is far more flammable than CAB dope.
nitriding. A method of case hardening steel. The steel to be case hardened is placed in a retort (a sealed,
high-temperature furnace) and heated to a specified high temperature while it is surrounded by ammonia
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航空术语词典Dictionary of Aeronautical Terms 中(145)
