# Frame of Reference - Key terms

### ABSOLUTE:

Fixed; not dependent on anything else. The value of 10 is absolute, relating to unchanging numerical principles; on the other hand, the value of 10 dollars is relative, reflecting the economy, inflation, buying power, exchange rates with other currencies, etc.

### CALIBRATION:

The process of checking and correcting the performance of a measuring instrument or device against a commonly accepted standard.

### CARTESIAN COORDINATE SYSTEM:

A method of specifying coordinates in relation to an x-axis, y-axis, and z-axis. The system is named after the French mathematician and philosopher René Descartes (1596-1650), who first described its principles, but it was developed greatly by French mathematician and philosopher Pierre de Fermat (1601-1665).

### COEFFICIENT:

A number that serves as a measure for some characteristic or property. A coefficient may also be a factor against which other values are multiplied to provide a desired result.

### COORDINATE:

A number or set of numbers used to specify the location of a point on a line, on a surface such as aplane, or in space.

### FRAME OF REFERENCE:

The perspective of a subject in observing an object.

### OBJECT:

Something that is perceived or observed by a subject.

### RELATIVE:

Dependent on something else for its value or for other identifyingqualities. The fact that the United States has a constitution is an absolute, but th efact that it was ratified in 1787 is relative: that date has meaning only within the Western calendar.

### SUBJECT:

Something (usually a person) that perceives or observes an object and/or its behavior.

### X-AXIS:

The horizontal line of reference for points in the Cartesian coordinatesystem.

### Y-AXIS:

The vertical line of reference for points in the Cartesian coordinate system.

### Z-AXIS:

In a three-dimensional version of the Cartesian coordinate system, the z-axis is the line of reference for points in the third dimension. Typically the x-axisequates to "width," the y-axis to "height," and the z-axis to "depth"—though in factlength, width, and height are all relative to the observer's frame of reference.