# Active Physics Vocabulary Table (2004)

acceleration | The rate at which an object's velocity changes with time. It involves a change in the speed (increase or decrease) OR direction OR both speed and direction. |

amplitude | The height of the wave |

centimeter | A unit of measure in the metric system of measurement equivalent to 1/100 of a meter or 0.3927 inch; abbreviated is cm. |

centripetal force | The force making a motion is a circle possible, always directed to the center of the circle |

constructive interference | When waves align and the resulting wave has troughs and humps that are larger. |

controlled variable | An object or condition you want to remain constant when you carry out a scientific investigation. |

destructive interference | When waves align and the resulting wave has troughs and humps that are smaller. |

electromagnetic | Relating to the interplay between electric and magnetic fields. In particular, light (as well as x-rays, microwaves, gamma rays, etc.) |

electromagnetic waves | Radiation consisting of waves of energy sent through space and matter associated with electric and magnetic fields resulting from the acceleration of an electric charge |

force | Push or pull that gives energy to an object, sometimes causing a change in the motion of the object. |

frame of reference | Any system for specifying the precise location of objects in space |

frequency | The number of back-and-forth cycles per second, in a wave or wave-like process. |

friction | A force that resists motion between two objects in contact. |

g | A unit of mass |

gravitational field | Field created by any object with mass, extending outward in all directions, which determines the influence of that object on all others. |

Heat | The transfer of energy from one object at a higher temperature to another object at a lower temperature. |

hologram | Laser-generated image with three-dimensional properties |

inertia | The tendency of matter to remain at rest if at rest or to remain in motion in a straight line if in motion. |

kgm/s^{2} |
The base units that make up a Newton (a unit of force) |

kinetic energy | The energy possessed by a moving object. = ½ mv^{2} |

longitudinal waves | A wave in which the individual particles of a medium vibrate back and forth in the direction in which the wave travels. Sound is this type of wave |

m | A unit of length equal to 1 meter |

m/s | A unit of speed meters per second |

m/s^{2} |
A unit of acceleration meters per second squared |

manipulated variable | Object or condition that you change on purpose to test your hypothesis |

mass | A measure of how much material something contains. This shouldn't be confused with weight, which is a measure of the force of gravity on an object. |

mechanical waves | Waves which travel through a medium Sound waves, water waves and waves in solid objects |

meter | The standard unit of length in the SI system of measure that equals 39.37 inches. |

momentum | Mass times velocity; a quantity that determines the potential force that an object can impart to another object by collision |

motion | A change in the position or location of one thing with respect to another |

net force | Sum of all the forces acting on an object |

photovoltaic cell | An electronic device consisting of layers of semiconductor materials that is capable of converting light directly into electricity. |

potential energy | Stored energy of a material, a result of its position in an electric, magnetic, or gravitational field PE=mgh |

primary or P waves, | P waves, or compressional wave, are seismic body waves that shakes the ground back and forth in the same direction as the direction the wave is moving. |

reflection | The change in direction (or return) of waves striking a surface |

refraction | Waves change direction as they pass from one medium to another. |

responding variable | Object or condition that changes when you change the manipulated variable in a scientific investigation. |

secondary or S | S waves, are seismic body waves that shakes the ground back and forth perpendicular to the direction the waves are moving |

SI system | A complete system of units of measurement for scientists; fundamental quantities are length (meter) and mass (kilogram) and time (second) and electric current (ampere) and temperature (Kelvin) and amount of matter (mole) and luminous intensity (candela) |

slope of graph | The mathematical result of the change in the y axis of a line divided by the corresponding change on the x axis |

sound | Mechanical energy vibrations transmitted as waves through a solid, liquid, or a gas that can be detected by the human ear |

speed | Distance traveled per unit time |

speed of light | The speed at which electromagnetic radiation propagates in a vacuum; it is defined as 299 792 458 m/s |

standing wave | A wave that appears to be standing still; it occurs when waves with the same frequency (and wavelength) moving in opposite directions interfere with each other |

subsystem | A major part of a system which itself has the characteristics of a system |

system | Group of interacting, interrelated, or interdependent parts made up of matter and energy that form a complex whole |

thermal energy | Energy in the form of heat. The total internal kinetic and potential energy of an object due to the random motion of its atoms and molecules. |

thought experiment | An experiment that cannot be or is not carried out in practice; it is reasoned through by thought and intuition. |

transverse waves | A wave in which the vibrations of the medium are perpendicular to the direction the wave is moving |

unbalanced force | A force that is not countered by another force in the opposite direction. |

vector | A measurement having both magnitude and direction, velocity, acceleration and force It may be represented as a directed line segment |

velocity | Rate of change of position or direction of an object |

wave crest | The highest part of a wave. The curved tops or ridges of an oscillating wave. |

wave interference | The superposition (overlapping) of two or more waves resulting in a new wave pattern |

wave medium | The material that can carry a mechanical wave |

wave period | The time elapsed for a wave to travel the distance of one wavelength. |

wave speed | The velocity of a traveling wave |

wave superposition | The addition of two or more waves to produce a new wave. |

wave trough | The lowest part of a wave, between successive crests |

wavelength | The distance measured from crest to crest of one complete wave or cycle. |

weight | The force of gravity acting on a body, equal to the mass of the body multiplied by the acceleration of gravity |

work | The transfer of energy from one object or system to another by applying a force over a distance. The formula is (force) x (distance). |