SAT II物理考试常用术语汇总之S.

　　SAT2考试时间为一小时，大部分为选择题，主要考察学生某一专业的知识，每科满分为800分，学生可以根据所申请的各专业和学校的要求参加。下面提供SAT2物理考试常用术语汇总的S部分。

　　S

　　Scalar

　　A quantity that possesses a magnitude but not a direction. Mass and length are common examples.

　　Second Law of Thermodynamics

　　There are a few versions of this law. One is that heat flows spontaneously from hot to cold, but not in the reverse direction. Another is that there is no such thing as a 100% ficient heat engine. A third states that the entropy, or disorder, of a system may increase but will never decrease spontaneously.

　　Significant digits

　　The number of digits that have been accurately measured. When combining several measurements in a formula, the resulting calculation can only have as many significant digits as the measurement that has the smallest number of significant digits.

　　Simple harmonic oscillator

　　An object that moves about a stable equilibrium point and experiences a restoring force that is directly proportional to the oscillator’s displacement.

　　Sine

　　In a right triangle, the sine of a given angle is the length of the side opposite the angle divided by the length of the hypotenuse.

　　Snell’s Law

　　Relates the angle of incidence to the angle of rraction: .

　　Sound

　　Waves carried by variations in air pressure. The speed of sound waves in air at room temperature and pressure is roughly 343 m/s.

　　Specific heat

　　The amount of heat of a material required to raise the temperature of either one kilogram or one gram of that material by one degree Celsius. Different units may be used depending on whether specific heat is measured in s of grams or kilograms, and joules or calories.

　　Spectroscope

　　A device that breaks incoming light down into spectral rays, so that one can see the exact wavelength constituents of the light.

　　Speed

　　A scalar quantity that tells us how fast an object is moving. It measures the rate of change in distance over time. Speed is to be contrasted with velocity in that there is no direction associated with speed.

　　Spring

　　Objects that experience oscillatory or simple harmonic motion when distorted. Their motion is described by Hooke’s Law.

　　Spring constant

　　Indicates how “bouncy” or “stiff” a spring is. More specifically, the spring constant, k, is the constant of proportionality between the restoring force exerted by the spring, and the spring’s displacement from equilibrium. The greater the value of k, more resistant the spring is to being displaced.

　　Standing wave

　　A wave that interferes with its own rlection so as to produce oscillations which stand still, rather than traveling down the length of the medium. Standing waves on a string with both ends tied down make up the harmonic series.

　　Static friction

　　The force between two surfaces that are not moving relative to one another. The force of static friction is parallel to the plane of contact between the two objects and resists the force pushing or pulling on the object.

　　Strong nuclear force

　　The force that binds protons and neutrons together in the atomic nucleus.

　　Sublimation

　　The process by which a solid turns directly into gas, because it cannot exist as a liquid at a certain pressure.

　　Superposition

　　The principle by which the displacements from different waves traveling in the same medium add up. Superposition is the basis for interference.

　　System

　　A body or set of bodies that we choose to analyze as a group.