Chapter 1 - An Introduction to Physics

1.1 Law and Theory

• Law - A description of a relationship in Nature that manifests itself in recurring patterns of events.

• Theory - A construct of definitions, hypotheses, and laws that explain some observed order in Nature

1.3 Length

• International Systems of Units ("Système International d'Unités“ SI

• U.S. Customary Units

System International SI

The metric system is an international decimalized system of measurement, first adopted by France in 1791, that is the common system of measuring units used by most of the world. Since the 1960s the International System of Units ("Système International d'Unités" in French, hence "SI") has been the internationally recognized standard metric system. Metric units are universally used in scientific work, and widely used around the world for personal and commercial purposes.

SI Prefixes

Length Equivalents

Volume Equivalents

1.4 Mass and Weight

How are Mass and Weight different.

1. Mass is a measurement of the amount of matter something contains, while Weight is the measurement of the pull of gravity on an object.

2. Mass is measured by using a balance comparing a known amount of matter to an unknown amount of matter. Weight is measured on a scale.

3. The Mass of an object doesn't change when an object's location changes. Weight, on the other hand does change with location.

Mass and Weight Correspondence on Earth

1.5 Time

Time has been defined as the continuum in which events occur in succession from the past to the present and on to the future. Time has also been defined as a one-dimensional quantity used to sequence events, to quantify the durations of events and the intervals between them, and (used together with other quantities such as space) to quantify and measure the motions of objects and other changes.

1.6 Significant Figures

• Addition and Subtraction - The result of addition and/or subtraction should be rounded off so that it has the same number of decimal places (to the right of the decimal point) as the quantity in the calculation having the least number of decimal places.

Example Significant Figures + and -

0.1402.02.1

+

1.6 Significant Figures

• Multiplication and Division - The result of multiplication and/or division should be rounded off so that it has as many significant figures as the least precise quantity used in the calculation.

Example Significant Figures * and /

10.75 3.54

38.10

×4300

53753225

1.6 Significant Figures

• Sines and Cosines - The values of trigonometric functions have the same number of significant figures as their arguments.

1.6 Significant Figures

• Rounding – Because rounding off intermediate numbers within a calculation can produce cumulative errors, one or two insignificant figures should be carried through intermediate calculations and only the final answers should be properly rounded off.

Examples of Significant Figures

1. 1 m2. 0.7 g3. 0.04 km4. 0.02 x 1025

5. 9 x 108

Examples of Significant Figures

1. 5.00 m2. 600 nm3. 0.300 cm4. 0.0200 kg5. 4.00 x 1012