# Active Physics Vocabulary List (2005)

## Misc

- accuracy
- How close the measured value is to the standard or accepted value of that measurement.
- 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.
- controlled variable
- An object or condition you want to remain constant when you carry out a scientific investigation.
- g
- A unit of mass.
- m
- A unit of length equal to 1 meter.
- m/s
- A unit of speed meters per second.
- 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.
- meter
- The standard unit of length in the SI system of measure that equals 39.37 inches.
- responding variable
- Object or condition that changes when you change the manipulated variable in a scientific investigation.
- 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.
- 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.
- thought experiment
- An experiment that cannot be or is not carried out in practice; it is reasoned through by thought and intuition.

## Chapter 2 Motion

- 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.
- centripetal force
- The force making a motion is a circle possible, always directed to the center of the circle.
- 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.
- friction
- A force that resists motion between two objects in contact.
- Heat
- The transfer of energy from one object at a higher temperature to another object at a lower temperature.
- 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}. - m/s
^{2} - A unit of acceleration meters per second squared.
- 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.
- potential energy
- Stored energy of a material, a result of its position in an electric, magnetic, or gravitational field. PE=mgh.
- 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.
- unbalanced force
- A force that is not countered by another force in the opposite direction.
- vector
- A measurement having both magnitude and direction. It may be represented as a directed line segment.
- velocity
- Rate of change of position or direction of an object.
- 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).

## Chapter 3 Waves

- amplitude
- The height of the wave.
- constructive interference
- When waves align and the resulting wave has troughs and crests that are larger.
- destructive interference
- When waves align and the resulting wave has troughs and crests that are smaller.
- 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 (light, x-rays, microwaves, gamma rays, etc.).
- frequency
- The number of back-and-forth cycles per second, in a wave or wave-like process.
- gravitational field
- Field created by any object with mass, extending outward in all directions, which determines the influence of that object on all others.
- hologram
- Laser-generated image with three-dimensional properties.
- 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.
- mechanical waves
- Waves which travel through a medium - sound waves, water waves and waves in solid objects.
- photovoltaic cell
- An electronic device consisting of layers of semiconductor materials that is capable of converting light directly into electricity.
- primary waves
- P waves, or compression waves, 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.
- secondary waves
- S waves, are seismic body waves that shakes the ground back and forth perpendicular to the direction the waves are moving.
- transverse waves
- A wave in which the vibrations of the medium are perpendicular to the direction the wave is moving.
- 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 for one wavelength to pass a point. The time for a wave to travel the distance of one wavelength. P= 1/frequency.
- wave speed
- The velocity of a traveling wave (distance traveled per time).
- 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.
- wave
- A rhythmic disturbance that transfers energy from place to place.
- wavelength
- The distance measured from crest to crest of one complete wave or cycle.