SAT词汇的掌握是大家取得SAT考试好成绩的基础，今天小编为大家提供了有关物理学的词汇，以下是详细内容。

　　Optics

　　The study of the properties of visible light, i.e., the portion of the electromagnetic spectrum with wavelengths between 360 and 780 nm (1 nm = m/s).

　　Orbit

　　When an object is held in circular motion about a massive body, like a planet or a sun, due to the force of gravity, that object is said to be in orbit. Objects in orbit are in perpetual free fall, and so are therefore weightless.

　　Oscillation

　　A back-and-forth movement about an equilibrium position. Springs, pendulums, and other oscillators experience harmonic motion.

　　Neutrino

　　An almost massless particle of neutral charge that is released along with a beta particle in beta decay.

　　Neutron

　　A neutrally charged particle that, along with protons, constitutes the nucleus of an atom.

　　Neutron number

　　The number, N, of neutrons in an atomic nucleus.

　　Newton

　　A unit of force: 1 N is equivalent to a 1 kg · m/s2.

　　Newton’s First Law

　　An object at rest remains at rest, unless acted upon by a net force. An object in motion remains in motion, unless acted upon by a net force.

　　Newton’s Law of Universal Gravitation

　　The force of gravity, F, between two particles of mass and , separated by a distance r, has a magnitude of , where G is the gravitational constant. The force is directed along the line joining the two particles.

　　Newton’s Second Law

　　F = ma. The net force, F, acting on an object causes the object to accelerate, a. The magnitude of the acceleration is directly proportional to the net force on the object and inversely　proportional to the mass, m, of the object.

　　Newton’s Third Law

　　To every action, there is an equal and opposite reaction. If an object A exerts a force on another object B, B will exert on A a force equal in magnitude and opposite in direction to the force exerted by A.

　　Node

　　The points on a standing wave where total destructive interference causes the medium to remain fixed at its equilibrium position.

　　Normal

　　The line perpendicular to a surface. There is only one normal for any given surface.

　　Normal force

　　The reaction force of the ground, a table, etc., when an object is placed upon it. The normal force is a direct consequence of Newton’s Third Law: when an object is placed on the ground, the ground pushes back with the same force that it is pushed upon. As a result, the net force of an object on the ground is zero, and the object does not move.

　　Nuclear fission

　　A nuclear reaction in which a high-energy neutron bombards a heavy, unstable atomic nucleus, causing it to split into two smaller nuclei, and releasing some neutrons and a vast amount of energy at the same time.

　　Nuclear fusion

　　A nuclear reaction that takes place only at very high temperatures. Two light atoms, often hydrogen, fuse together to form a larger single atom, releasing a vast amount of energy in the process.

　　Nucleus

　　The center of an atom, where the protons and neutrons reside. Electrons then orbit this nucleus.