Physics 101: Chapter 1, Pg 1

Measurement Systems

Significant Figures

Dimensional Analysis

Physics 101: Physics 101: Chapter 1Chapter 1

Physics 101: Chapter 1, Pg 2

SI – International System US – British System Basic Metric Units

Quantity Length Mass Time El. Current TemperatureUnit meter kilogram second Ampere KelvinSymbol m kg s A K

Measurement SystemsMeasurement Systems

Physics 101: Chapter 1, Pg 3

Power Prefix Symbol10-18 atto a10-15 femto f10-12 pico p10-9 nano n10-6 micro 10-3 milli m103 kilo k106 mega M109 giga G1012 tera T1015 peta P1018 exa E

Si PrefixesSi Prefixes

Physics 101: Chapter 1, Pg 4

METRIC LINE

Tm Gm Mm km m mm um nm pm fm am LengthTg Gg Mg kg g mg ug ng pg fg ag MassTl Gl Ml kl l ml ul nl pl fl al Capacity

T - teraG - gigaM - megak - kilo Centerm - milliu - micro m - metern - nano g - gramp - pico l - literf - femto

Metric LineMetric Line

Physics 101: Chapter 1, Pg 5

METRIC TO ENGLISH ENGLISH TO METRIC

From Metric To English Multiply by From English To Metric Multiply by

meters yards 1.09 yards meters 0.91meters feet 3.28 feet meters 0.30centimeters inches 0.39 inches centimeters 2.54kilometers miles 0.62 miles kilometers 1.61grams ounces 0.035 ounces grams 28.35kilograms pounds 2.20 pounds kilograms 0.45liters quarts 1.06 quarts liters 0.95liters gallons 0.26 gallons liters 3.78

Conversion TableConversion Table

Physics 101: Chapter 1, Pg 6

Conversion of Fahrenheit to Celsius

9

)32(5

FC

Conversion of Celsius to Fahrenheit

325

9

CF

Temperature ConversionTemperature Conversion

Physics 101: Chapter 1, Pg 7

Example 1: Convert 50 mph to m/s.

From 1 mile = 1609 m:

Example 2: A hall bulletin board has an area of 2.5 m2. What is this area in cm2?

Because 1m=100cm it is sometimes assumed that 1 m2 = 100 cm2, which is WRONG. The correct conversion is:

50 1609 122

3600

miles m h mm

h miles s s

2 2 4 22.5 2.5 2.5 100 100 25000 2.5 10m m m cm cm cm cm

Conversion into MetricConversion into Metric

Physics 101: Chapter 1, Pg 8

The number of significant figures of a numerical quantity is the number of reliably known digits it contains.

Zeros at the beginning of a number are not significant. They merely locate the decimal point. 0.254 - three significant figures (2, 5, 4)

Zeros within a number are significant 104.6 - four significant figures (1, 0, 4, 6)

Zeros at the end of a number after the decimal point are significant: 2705.0 - five significant figures (2, 7, 0, 5, 0)

Significant FiguresSignificant Figures

Physics 101: Chapter 1, Pg 9

The FINAL result of a multiplication or division should have the same number of significant figures as the quantity with the least number of significant figures that was used in the calculation.

The FINAL result of the addition or subtraction of numbers should have the same number of decimal places as the quantity with the least number of decimal places that was used in the calculation.

Significant Figures - ConclusionSignificant Figures - Conclusion

Physics 101: Chapter 1, Pg 10

Example 1:

Find the area of a room 2.4 m by 3.65 m:

2.4m x 3.65m = 8.76m2=8.8m2

Rounded to 2 s.f. - because 2 is least # of s.f.

Example 2:

Given the numbers 23.25, 0.546, and 1.058 add the first two subtract the least number from the first

Significant Figures - PracticeSignificant Figures - Practice

Physics 101: Chapter 1, Pg 11

The two sides of an equation must be equal not only in numerical value, but also in dimensions (BOTH SIDES OF THE EQUATION ARE NUMERICALLY AND DIMENSIONALLY EQUAL). And dimensions can be treated as algebraic quantities.

[L] - Length [M] - Mass [T] - Time

Dimensional AnalysisDimensional Analysis

Physics 101: Chapter 1, Pg 12

Example 1:

Is an equation x = v t

a correct equation? x - is the distance in m v = is the velocity in m/s t - is the time in s

Dimensionally the equation is:

Example 2:

Is an equation x = a t2

a correct equation? a is acceleration in m/s2

][][][

][][ LTT

LL

][][][

][][ 2

2 LTT

LL

Dimensional Analysis - PracticeDimensional Analysis - Practice

Physics 101: Chapter 1, Pg 13

Show that the equation x = xo + vt,

where v is velocity, x and xo are lengths, ant t is time, is dimensionally correct.

A Boeing 777 jet has a length of 209 ft. 1 inch, and wingspan of 199 ft and 11 inches. What are these dimensions in meters?

Determine the number of significant figures:

1.007 m 8.03 m 16.272 kg 0.015 µs

The two sides of right triangle are 8.7 cm (two significant figures) and 10.5 cm (three significant figures). What is the area of the triangle?

PracticePractice