General Science Knowledge

Absolute Zero: The theoretical lowest temperature possible at which all molecular motion ceases. Absolute zero, 0 K or -273.15°C, has never been reached.

 

Acceleration: The change in an object's velocity over time, measured in distance per unit time per unit time (for example meters per second per second or m/s2). Acceleration (a) is calculated by dividing the change (symbolized by Δ, the Greek letter delta) in velocity (v) by the change in time (t): a=Δv/ Δt. 

 

Atom: The smallest unit of an element that retains the chemical properties of the element. Atoms can exist alone or in combinations with other atoms forming molecules.

 

Combustion: Commonly referred to as burning, a chemical reaction between a fuel (for example wood) and an oxidizing agent (for example oxygen) that produces heat (and usually, light).

 

Density: A measure of the compactness of a substance given by the mass per unit volume (d=m/v). Common units of density include g/ml, g/cm3, and kg/L. A measure of lead is not heavier than an equivalent measure of styrofoam, it is denser.

 

Endothermic: A process or reaction that absorbs heat. For example, ice melting is an example of an endothermic process because it absorbs heat from its surroundings.

 

Energy: An abstract property defined as the capacity to do work. The basic forms of energy include chemical, electrical, mechanical, nuclear, and radiant (light).

 

Exothermic: A process or reaction that releases heat. Wood burning in the presence of oxygen is an example of an exothermic reaction.

First Law of Thermodynamics: The First Law explores the conservation of energy. Specifically, this law explains that energy cannot be created or destroyed, only transformed from one form to another. It also states that the energy within a closed system is fixed – it cannot increase or decrease. The First Law is often expressed as an equation: ∆U=Q - W, or the change in internal energy (∆U) equals the heat added to the system (Q) minus the work done by the system (W).

 

Force: An influence (a "push or pull") that changes the motion of a moving object (e.g., slows it down, speeds it up, changes its direction) or produces motion in a stationary object. The strength of a force is calculated by multiplying the mass of the object by its acceleration. In the metric (or SI) system, force is measured in newtons.

 

Frequency: The rate at which a vibration occurs that constitutes a wave, either in a material or in an electromagnetic field, usually measured in hertz (Hz).

 

Heat: A measure of the total internal energy of a substance that can be increased or decreased when objects with different temperatures are placed into contact. Heat is a process, not a property of a material.

 

Joule: A metric unit measuring energy or work and named for the British scientist James Prescott Joule. One joule (J) represents the amount of work that can be done by a force of one newton (N) acting over a distance of one meter (m): J=1 N·m  or  J=1 kg·m2/s2.

 

Kinetic Energy: The energy an object possesses by virtue of its motion. An object of mass m moving at velocity v has a kinetic energy of ½m·v2.

 

Mass:A fundamental property of matter which is a numerical measure of the inertia of an object or the amount of matter that an object contains. The mass of an object is different from its weight as mass is independent of the gravitational field exerted on an object.

 

Newton: A metric unit measuring force and named for English physicist Isaac Newton. One newton (N) represents the force needed to accelerate a one-kilogram (kg) object 1 meter (m) per second (s) per second (s): N=kg·m/s2.

 

Potential energy: The energy an object possesses by virtue of its position in relation to a field of force. For example, lifting a mass m by h meters increases its potential energy by m·g·h, where g is the acceleration due to gravity.

 

Second Law of Thermodynamics: The Second Law is commonly referred to as the Law of Increased Entropy. During the conversion of energy from one form to another, some energy is lost to the process of conversion. Though the total energy is in fact conserved, a portion becomes unusable as it increases disorder and randomness within the system.

 

Third Law of Thermodynamics: The Third Law was developed between 1906 and 1912 by the chemist Walter Nernst and relates specifically to entropy. Nernst identifies that, within a perfect crystal, entropy corresponds to temperature. As the temperature reaches absolute zero, so does the entropy (absolute entropy). Though not physically possible, this defines the mathematical limit of the universe and serves as a reference point for measuring entropy.

 

Velocity:The speed at which an object is traveling, measured in distance per unit time (for example meters per second or m/s). Compare to acceleration.

 

Wavelength: The distance between corresponding points on two successive waves, generally measured from crest to crest.

 

Weight: A measure of the force exerted on an object by a gravitational field. The weight of an object equals its mass times the force of gravity: w=m*g.

 

Work: A process that occurs when a force acts over a distance, as when an object is moved. Work equals the multiple of the applied force by distance: W=F*d. Work can be thought of as a process in which one form of energy is transformed into another and is commonly expressed in units of joules.

 

Visionlearning, 2015, Glossary (by discipline), viewed 26 January 2015, http://www.visionlearning.com/en/glossary/discipline/Physics