sat考試物理方面必備詞彙

物理是SAT考試的一個難點，考生有必要在物理方面多準備一些重要的.高頻詞彙。本站小編為大家精心準備了sat考試關於物理方面必備的一些詞彙，歡迎大家前來閲讀。

Impulse

A vector quantity defined as the product of the force acting on a body multiplied by the time interval over which the force is exerted.

Incident ray

When dealing with reflection or refraction, the incident ray is the ray of light before it strikes the reflecting or refracting surface.

Inclined plane

A wedge or a slide. The dynamics of objects sliding down inclined planes is a popular topic on SAT II Physics.

Index of refraction

The index of refraction n = c/v of a substance characterizes the speed of light in that substance, v. It also characterizes, by way of Snell's Law, the angle at which light refracts in that substance.

Induced current

The current induced in a circuit by a change in magnetic flux.

Inelastic collision

A collision in which momentum is conserved but kinetic energy is not.

Inertia

The tendency of an object to remain at a constant velocity, or its resistance to being accelerated. Newton’s First Law is alternatively called the Law of Inertia because it describes this tendency.

Inertial reference frame

A reference frame in which Newton’s First Law is true. Two inertial reference frames move at a constant velocity relative to one another. According to the first postulate of Einstein’s theory of special relativity, the laws of physics are the same in all inertial reference frames.

Instantaneous velocity

The velocity at any given instant in time. To be contrasted with average velocity, which is a measure of the change in displacement over a given time interval.

Internal energy

The energy stored in a thermodynamic system.

Inversely proportional

Two quantities are inversely proportional if an increase in one results in a proportional decrease in the other, and a decrease in one results in a proportional increase in the other. In a formula defining a certain quantity, those quantities to which it's inversely proportional will appear in the denominator.

Isolated system

A system that no external net force acts upon. Objects within the system may exert forces upon one another, but they cannot receive any impulse from outside forces. Momentum is conserved in isolated systems.

Isotope

Atoms of the same element may have different numbers of neutrons and therefore different masses. Atoms of the same element but with different numbers of neutrons are called isotopes of the same element.

Kelvin

A scale for measuring temperature, defined such that 0K is the lowest theoretical temperature a material can have. 273K = 0oC.

Kepler’s First Law

The path of each planet around the sun is an ellipse with the sun at one focus.

Kepler’s Second Law

If a line is drawn from the sun to the planet, then the area swept out by this line in a given time interval is constant.

Kepler’s Third Law

Given the period, T, and semimajor axis, a, of a planet’s orbit, the ratio is the same for every planet.

Kinematic equations

The five equations used to solve problems in kinematics in one dimension with uniform acceleration.

Kinematics

Kinematics is the study and description of the motion of objects.

Kinetic energy

Energy associated with the state of motion. The translational kinetic energy of an object is given by the equation .

Kinetic friction

The force between two surfaces moving relative to one another. The frictional force is parallel to the plane of contact between the two objects and in the opposite direction of the sliding object’s motion.

Kinetic theory of gases

A rough approximation of how gases work, that is quite accurate in everyday conditions. According to the kinetic theory, gases are made up of tiny, round molecules that move about in accordance with Newton’s Laws, and collide with one another and other objects elastically. We can derive the ideal gas law from the kinetic theory.

Magnetic flux

The dot product of the area and the magnetic field passing through it. Graphically, it is a measure of the number and length of magnetic field lines passing through that area. It is measured in Webers (Wb).

Magnification

The ratio of the size of the image produced by a mirror or lens to the size of the original object. This number is negative if the image is upside-down.

Magnitude

A property common to both vectors and scalars. In the graphical representation of a vector, the vector’s magnitude is equal to the length of the arrow.

Margin of error

The amount of error that’s possible in a given measurement.

Mass

A measurement of a body’s inertia, or resistance to being accelerated.

Mass defect

The mass difference between a nucleus and the sum of the masses of the constituent protons and neutrons.

Mass number

The mass number, A, is the sum of the number of protons and neutrons in a nucleus. It is very close to the weight of that nucleus in atomic mass units.

Maxima

In an interference or diffraction pattern, the places where there is the most light.

Mechanical energy

The sum of a system’s potential and kinetic energy. In many systems, including projectiles, pulleys, pendulums, and motion on frictionless surfaces, mechanical energy is conserved. One important type of problem in which mechanical energy is not conserved is the class of problems involving friction.

Medium

The substance that is displaced as a wave propagates through it. Air is the medium for sound waves, the string is the medium of transverse waves on a string, and water is the medium for ocean waves. Note that even if the waves in a given medium travel great distances, the medium itself remains more or less in the same place.

Melting point

The temperature at which a material will change phase from solid to liquid or liquid to solid.

Meson

A class of elementary particle whose mass is between that of a proton and that of an electron. A common kind of meson is the pion.

Michelson-Morley experiment

An experiment in 1879 that showed that the speed of light is constant to all observers. Einstein used the results of this experiment as support for his theory of special relativity.

Minima

In an interference or diffraction pattern, the places where there is the least light.

Mole

The number of hydrogen atoms in one gram of hydrogen, equal to . When counting the number of molecules in a gas, it is often convenient to count them in moles.