## Comment on Key Terms from Glossary

Browse the glossary using this index

Special | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | ALL

### A

#### accuracy

the degree to which a measured value agrees with correct value for that measurement

#### approximation

an estimated value based on prior experience and reasoning

### C

#### classical physics

physics that was developed from the Renaissance to the end of the 19th century

#### conversion factor

a ratio expressing how many of one unit are equal to another unit

### D

#### derived units

units that can be calculated using algebraic combinations of the fundamental units

### E

#### English units

system of measurement used in the United States; includes units of measurement such as feet, gallons, and pounds

### F

#### fundamental units

units that can only be expressed relative to the procedure used to measure them

### K

#### kilogram

the SI unit for mass, abbreviated (kg)

### L

#### law

a description, using concise language or a mathematical formula, a generalized pattern in nature that is supported by scientific evidence and repeated experiments

### M

#### meter

the SI unit for length, abbreviated (m)

the percent uncertainty in a quantity calculated by multiplication or division is the sum of the percent uncertainties in the items used to make the calculation

#### metric system

a system in which values can be calculated in factors of 10

#### model

representation of something that is often too difficult (or impossible) to display directly

#### modern physics

the study of relativity, quantum mechanics, or both

### O

#### order of magnitude

refers to the size of a quantity as it relates to a power of 10

### P

#### percent uncertainty

the ratio of the uncertainty of a measurement to the measured value, expressed as a percentage

#### physical quantity

a characteristic or property of an object that can be measured or calculated from other measurements

#### physics

the science concerned with describing the interactions of energy, matter, space, and time; it is especially interested in what fundamental mechanisms underlie every phenomenon

#### precision

the degree to which repeated measurements agree with each other

### Q

#### quantum mechanics

the study of objects smaller than can be seen with a microscope

### R

#### relativity

the study of objects moving at speeds greater than about 1% of the speed of light, or of objects being affected by a strong gravitational field

### S

#### scientific method

a method that typically begins with an observation and question that the scientist will research; next, the scientist typically performs some research about the topic and then devises a hypothesis; then, the scientist will test the hypothesis by performing an experiment; finally, the scientist analyzes the results of the experiment and draws a conclusion

#### second

the SI unit for time, abbreviated (s)

#### SI units

the international system of units that scientists in most countries have agreed to use; includes units such as meters, liters, and grams

#### significant figures

express the precision of a measuring tool used to measure a value

### T

#### theory

an explanation for patterns in nature that is supported by scientific evidence and verified multiple times by various groups of researchers

### U

#### uncertainty

a quantitative measure of how much your measured values deviate from a standard or expected value

#### units

a standard used for expressing and comparing measurements