Measurement

What is measurement?• The process of comparing the

quantity of an observable relative to a standard.

Example:– Measuring the length of pencil using a

ruler– Determining how heavy you are using a

weighing scale

How should measurements be reported?

• All measurements must be given with the correct units.

• All measurements must be given with the correct number of significant figures (sf’s).

English System of Measurement

• This system grew out of the creative ways that people measured for themselves. Familiar objects and parts of the body were used as measuring devices.

English System of Measurement

• This system grew out of the creative ways that people measured for themselves. Familiar objects and parts of the body were used as measuring devices.

English System of Measurement

• Unfortunately, these creative measuring devices allowed for different measurements to be obtained when different people measured the same items.

• Eventually, a standard was set so that all measurements represented the same amount for everyone.

Conversion within the English SystemLength:

12 inches (in) = 1 foot (ft)3 feet = 1 yard (yd)5280 feet = 1 mile (mi)

Weight:16 ounces (oz) = 1 pound (lb)2000 lb = 1 ton

Conversion within the English System

Capacity:3 teaspoons (tsp) = 1 tablespoon (tbsp)

16 tbsp = 1 cup (c)8 ounces (oz) = 1 c2 c = 1 pint (pt)2 pt = 1 quart (qt)4 qt = 1 gallon (gal)

International System of UnitsSysteme International des Unites

• This is the modern form of the metric system and is generally a system of units of measurement devised around seven base units and the convenience of the number ten.

• It is the world's most widely used system of measurement, both in everyday commerce and in science.

Advantages of SI over the English System

• More consistent measuring tools• Extensively used in science and

other related fields• Easier to convert units within the

system

SI Fundamental QuantitiesQuantity Unit (Symbol)

Mass (m) kilogram (kg)

Time (T) seconds (s)

Length (l) meter (m)

Temperature (T) kelvin (K)

Amount of Substance (n) mole (mol)

Luminous Intensity (I) candela (cd)

Current (I) ampere (A)

Conversion within the SI

What makes conversion between SI units is its extensive use of prefixes instead of arbitrary

SI Prefixes and EquivalentsPower of Ten Prefix Symbol

1024 yotta Y1021 zetta Z1018 exa E1015 peta P1012 tera T109 giga G106 mega M103 kilo k102 hecto h101 deca da

SI Prefixes and EquivalentsPower of Ten Prefix Symbol

10-1 deci d10-2 centi c10-3 milli m10-6 micro μ10-9 nano n10-12 pico p10-15 femto f10-18 atto a10-21 zepto z10-24 yocto y

Conversion within the SI

Time:1 hour (hr) = 60 minutes (min)1 minute = 60 seconds (s)time intervals shorter than a second uses the metric prefixes (e.g. ms, μs, ps)

Conversion within the SI

Temperature:K = °C + 273.15°C = K – 273.15

Conversion between English and SI1 inch = 2.54 cm2.2 lbs = 1 kg°F = 9/5 °C + 32°C = 5/9 (°F – 32)

Metric units:1 liter (L) = 1 000 milliliter (mL)1 mL = 1cm3

1000 L = 1 m3

fin

Convert the following observing proper units and correct number of significant figures.

1. 125 m ? Km2. 20.0 cm ? In3. 160 mi ? Km4. 25 kg ? Lbs5. 1560 mg ? kg

TEMPERATURE• The degree of the hotness or the

coldness of a body (layman).• The measure of the average kinetic

energy of the particles of a body.

The Temperature Scales• The Fahrenheit Scale - based on 32

for the freezing point of water and 212 for the boiling point of water

• The scale is divided into 180 equal intervals

• Dwveloped in the 18th-century by the German physicist Daniel Gabriel Fahrenheit

The Temperature Scales• The Celsius Scale – also called the

centigrade scale• Based on 0 for the freezing point of

water and 100 for the boiling point of water

• Invented in 1742 by the Swedish astronomer Anders Celsius

The Temperature Scales• The Kelvin Scale - the base unit of

thermodynamic temperature measurement in the International System (SI) of measurement

• An absolute temperature scale named for the British physicist William Thomson Baron Kelvin

• Its zero point is in absolute zero, the theoretical temperature at which the molecules of a substance have the lowest energy

Conversion (oF and oC)

• F = 9/5C + 32• C = 5/9(F - 32)

Conversion (oF and K)

• C = K - 273• K= C + 273

Seatwork: ½ Pad Paper1. 56.0 oC oF K2. 89 oF oC K3. Find the temperature at which the

reading in both the oF Scale and the oC Scale is the same? Show your solution.

4. Explain or discuss the 2004 definition of MEASUREMENT in not more than 5 sentences.