Chapter 0: Introduction: The Nature of Science and Physics - Review Terms

Physics

The study of the interactions of energy, matter, space, and time, and the fundamental mechanisms underlying every phenomenon.

Law of Conservation of Energy

A principle stating that energy can change form but is never lost.

Model

A representation of something that is often too difficult or impossible to display directly, justified with experimental proof and accurate under limited situations.

Theory

A testable explanation for patterns in nature supported by scientific evidence and verified multiple times by various groups of researchers.

Law

A concise description of a generalized pattern in nature supported by scientific evidence and repeated experiments, often expressed in a single mathematical equation.

Principle

A less broadly applicable statement than a law, such as Pascal’s principle, which is applicable only in fluids.

Scientific Method

A process that typically begins with an observation and question, followed by research, hypothesis formulation, experimentation, and conclusion drawing.

Classical Physics

The branch of physics developed from the Renaissance to the end of the 19th century, applicable under conditions of low speeds, large objects, and weak gravitational fields.

Modern Physics

The branch of physics that includes relativity and quantum mechanics, dealing with very fast and very small phenomena.

Relativity

A theory in modern physics used when an object is traveling at greater than about 1% of the speed of light or experiences a strong gravitational field.

Quantum Mechanics

A theory in modern physics used for objects smaller than can be seen with a microscope.

Relativistic Quantum Mechanics

The combination of relativity and quantum mechanics, describing the behavior of small objects traveling at high speeds or experiencing a strong gravitational field.

Experimentation

The cornerstone of discovering natural laws, involving observation, data collection, and analysis to formulate models, theories, and laws.

Natural Philosophy

The study of nature, encompassing many fields including astronomy, biology, chemistry, physics, mathematics, and medicine, before the specialization into separate sciences.

Scientific Evidence

Objective evidence that supports scientific theories and laws, verified through repeated experimentation.

Physical Quantity

A physical quantity is defined by specifying how it is measured or by stating how it is calculated from other measurements.

SI Units

SI units, also known as the metric system, are the standard system of units agreed upon by scientists and mathematicians worldwide.

Fundamental SI Units

The fundamental SI units are meter (m) for length, kilogram (kg) for mass, second (s) for time, and ampere (A) for electric current.

Derived Units

Derived units are algebraic combinations of the fundamental units, such as speed, which is length divided by time.

Meter

The meter is the SI unit for length, defined as the distance light travels in a vacuum in 1/299,792,458 of a second.

Kilogram

The kilogram is the SI unit for mass, now defined in terms of the second, the meter, and Planck's constant.

Second

The second is the SI unit for time, defined as the duration of 9,192,631,770 vibrations of a cesium atom.

Metric Prefixes

Metric prefixes are symbols used to denote various factors of 10, such as kilo (k) for 10^3 and milli (m) for 10^-3.

Order of Magnitude

Order of magnitude refers to the scale of a value expressed in the metric system, indicating powers of 10.

Unit Conversion

Unit conversion involves changing a measurement from one unit to another using a conversion factor.

Conversion Factor

A conversion factor is a ratio expressing how many of one unit are equal to another unit, used in unit conversions.

English Units

English units, also known as the customary or imperial system, are used primarily in the United States.

Microscopic Standards

Microscopic standards refer to basing measurement standards on microscopic objects and fundamental physical phenomena.

Nonstandard Units

Nonstandard units are units not commonly used in scientific contexts, such as a firkin for volume.

Dimensional Analysis

Dimensional analysis is a method to convert one kind of unit to another using conversion factors.

Accuracy

How close a measurement is to the correct value for that measurement.

Precision

How close the agreement is between repeated measurements under the same conditions.

Uncertainty

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

Percent Uncertainty

The uncertainty of a measurement expressed as a percentage of the measured value, calculated as (δA/A)×100%.

Significant Figures

Digits in a measurement that are known with certainty plus the first uncertain digit.

Significant Figures in Multiplication and Division

The result should have the same number of significant figures as the quantity with the least significant figures entering into the calculation.

Significant Figures in Addition and Subtraction

The answer can contain no more decimal places than the least precise measurement.

Factors Contributing to Uncertainty

Include limitations of the measuring device, skill of the person making the measurement, irregularities in the object being measured, and other situational factors.

Zeros in Significant Figures

Zeros are significant except when they serve only as placekeepers.

Exact Numbers

Numbers that are known with complete certainty and do not affect the number of significant figures in a calculation.

Scaling

A method of estimating a larger or smaller quantity by using a known quantity as a reference.