Chapter 2: Physical Quantities and Measurements

pie graph

a circular graph resembling slices of a pie in which each slice represents the relative size of one part of a group in relation to the whole group

bar graph

a graph in which the height or length of columns or bars represent the values of data

box and whiskers plot

a graph of statistically aggregated data that uses a rectangle to represent the median 50% of the data and extension lines above and below to represent the extreme values or the upper and lower quartiles

linear regression

a mathematical technique for calculating the best straight line fit to a set of x-y data

correlation coefficient

a number between +1 and -1 which describes the goodness of fit for a regression

frequency table

a table in which a large data set data has been sorted into a smaller number of categories with each category representing a range of values or a count of items - useful for seeing large scale patterns in data with high point-to-point variability

measurement

communication of quantity that includes both a value and a unit.

precision

degree of mutual agreement among a series of measurements of the same quantity.

accuracy

how well a measurement's value agrees with a commonly accepted value.

mass

measure of the quantity of matter. Measured in units of kilograms in the International System of Units (SI). English units are slugs (rarely used).

temperature

measurement quantifying the degree of hot or cold of a substance;

scientific notation

method of writing numbers that uses a coefficient multiplied by a power of 10.

volume

number of cubic units that completely fill the interior space of an object.

decimal places

number of digits in a numerical value that are to the right of the decimal point.

surface area

number of square units that completely cover the exterior or exposed surface of an object.

matter

physical substance that has mass and takes up space.

inertia

property of matter that resists changes in speed or direction.

variable

quantity that may take on different values.

density

ratio of mass to volume or the mass per unit volume.

conversion factor

ratio used to transform a quantity expressed in one unit (or set of units) into another unit (or set of units)

model

relationship that connects variables, such as an equation or graph.

scale

relative size of things

macroscopic

scale that is large enough to be directly sensed, such as the scale of things in the everyday world.

microscopic

scale that is too small for direct observation with the senses. In physics, this is typically the size of atoms and molecules (or even smaller).

length

separation between two points. A fundamental measure of space with common units of meters, feet, and miles.

significant figures

those digits in a number that carry meaning as to the precision of the number or the measurement of it.

exponent

value of b in an expression ab.

dependent

variable in an experiment that changes in response to changes made in the independent variable.

independent variable

variable in an experiment that is typically changed by the experimenter in order to cause a change in the dependent variable.

error bars

vertical and horizontal lines added to the plotting of a data point to show the uncertainty in the x and y values