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。

　　Half-life

　　The amount of time it takes for one-half of a radioactive sample to decay.

　　Harmonic series

　　The series of standing waves supported by a string with both ends tied down. The first member of the series, called the fundamental, has two nodes at the ends and one anti-node in the middle. The higher harmonics are generated by placing an integral number of nodes at even intervals over the length of the string. The harmonic series is very important in music.

　　Heat

　　A transfer of thermal energy. We don’t speak about systems “having” heat, but about their “transferring” heat, much in the way that dynamical systems don’t “have” work, but rather “do” work.

　　Heat engine

　　A machine that operates by taking heat from a hot place, doing some work with that heat, and then exhausting the rest of the heat into a cool place. The internal combustion engine of a car is an example of a heat engine.

　　Heat transfer

　　A transfer of thermal energy from one system to another.

　　Hertz (Hz)

　　The units of frequency, defined as inverse-seconds (1 Hz = 1 s–1). “Hertz” can be used interchangeably with “cycles per second.”

　　Hooke’s Law

　　For an oscillating spring, the restoring force exerted by the spring is directly proportional to the displacement. That is, the more the spring is displaced, the stronger the force that will pull toward the equilibrium position. This law is expressed mathematically as F = –kx, where F is the restoring force and x is the displacement. The constant of proportionality, –k, is the spring constant.

　　Hypotenuse

　　The longest side of a right triangle, opposite to the right angle.

　　Gamma decay

　　A form of radioactivity where an excited atom releases a photon of gamma radiation, thereby returning to a lower energy state. The atomic structure itself does not change in the course of gamma radiation.

　　Gamma ray

　　An electromagnetic wave of very high frequency.

　　Gold foil experiment

　　An experiment by Ernest Rutherford that proved for the first time that atoms have nuclei.

　　Gravitational constant

　　The constant of proportionality in Newton’s Law of Gravitation. It reflects the proportion of the gravitational force and , the product of two particles’ masses divided by the square of the bodies’ separation. N · m2/kg2.

　　Gravitational Potential Energy

　　The energy associated with the configuration of bodies attracted to each other by the gravitational force. It is a measure of the amount of work necessary to get the two bodies from a chosen point of reference to their present position. This point of reference is usually chosen to be a point of infinite distance, giving the equation . Objects of mass m that are a height h above the surface of the earth have a gravitational potential energy of .

　　Ground state

　　In the Bohr model of the atom, the state in which an electron has the least energy and orbits closest to the nucleus.