MEASUREMENT WHAT IS PHYSICS THE METRIC SYSTEM METRIC PREFIXES DIMENSIONAL ANALYSIS SIGNIFICANT FIGURES CONVERSION OF UNITS ORDER OF MAGNITUDE NOTATION TRIGONOMETRY P P P P P P P P P

Physics is the study of how physical quantities are related. It is concerned with the understanding of the natural universe. Physics is based on experimental observation. Physics is organized into a set of physical laws having mathematical expressions. PHYSICS: Mechanics Thermodynamics Electromagnetism Relativity Quantum Mechanics

THE METRIC SYSTEM: The fundamental physical quantities of the metric system are: length, mass, and time. Metric system basic units: length: the meter mass:the gram time:the second

Metric prefixes are based on powers of 10. prefixpowerabbreviation tera10 12 T giga10 9 G mega10 6 M kilo10 3 K milli10 -3 m micro10 -6  nano10 -9 n pico p

MASS: Mass in kg: Universe10 52 (?) Milky Way Galaxy7x10 41 Earth6x10 24 Human7x10 1 Bacterium1x Electron9x10 -31

Lengths and Distances in m: Distance to most remote Quasar1x10 26 Distance to nearest Galaxy1x10 22 Distance to nearest Star4x10 16 Mean orbital radius of Earth4x10 11 Length of a housefly5x10 -3 Size of a living cell1x10 -5 Diameter of a proton1x10 -15

Time Intervals in s: Age of Universe5x10 17 Age of earth1x10 17 Average of college student6x10 8 One day9x10 4 Period of audible sound wave1x10 -3 Period of visible light wave2x Time for light to cross a proton3x10 -24

Dimensional Analysis: Physical units combine algebraically. a = acceleration [a] = L/T 2 x = distance [x] = L t = time interval [t] = T x = at 2 /2 L = (L/T 2 T 2 = L

EXAMPLE: Using the variables v and r for speed (meters per second) and distance (meters), combine them algebraically to form an acceleration, a (meters per second squared).

Significant Figures: Significant figures includes the first estimated digit. Multiplication or Division: 1.Calculate the result 2.The result has the same number of significant figures as the factor with the fewest. Zeros immediately to the right of a decimal point are not significant unless they are by themselves. Zeros on the end of a number (5200) may or may not be significant or 5.2x10 3 Adding and Subtracting: The result has the same number of decimal places as the value with the fewest.

Conversion of Units: All conversion factors begin with an equation: x = y. All conversion factors are equal to 1 (unity). If x = y, then x/y = 1 and y/x = 1. Chose the ratio that eliminates the original unit. 100 cm = 1 m 52 cm = 52 cm x 1m/100cm = 0.52 m

EXAMPLE:Convert 67 miles per hour to meters per second. 1 mile = 1609 meters1 hour = 3600 seconds EXAMPLE:Convert cm 2 to m 2.

EXAMPLE:Convert 67 miles per hour to meters per second. 1 mile = 1609 meters1 hour = 3600 seconds EXAMPLE:Convert cm 2 to m mi/hr 1 mi 1609 m 1 hr s = m/s cm 2 (100 cm) 2 (1 m) 2 = m 2

Order of Magnitude Calculation: An order of magnitude calculation is done by selecting reasonable sized values to substitute into an equation. The purpose is to determine the size of the real calculation result. EXAMPLE:How much tire tread is worn off a tire for every mile driven?

A tire lasts about 40,000 miles and takes off about 1 cm of tread. Thus about 2.5x10 -7 m/mile of tread is removed. The important value is the power of 10.

NOTATION:  means change in.  means sum of.

Trigonometry: c b a  The trigonometric functions are most easily understood as ratios of the lengths of the sides of a right triangle.

Solve the triangle for the unknown sides. 40 o 8 X= ______ Y= _____

Solve the triangle for the unknown sides. 40 o 8 X= ______ Y= _____

Problem Solving: Read the problem carefully. Draw a diagram or sketch of the problem, don’t be an artist. Identify given information. Select basic relationship that applies. Substitute data and calculate result.