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Measure This. Space, the final frontier. The measurement of the space taken up by a sample of matter is the volume . We measure the volume of liquids in graduated cylinders. We measure the volume of gases in volumetric tanks.
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Space, the final frontier. • The measurement of the space taken up by a sample of matter is the volume. • We measure the volume of liquids in graduated cylinders. • We measure the volume of gases in volumetric tanks. • We measure volume for regular shaped solids by multiplying the length times the width times the height. l*w*h = v • We measure volume for irregular shapes by liquid displacement. vf – vi = v
Volume Readings- • Meniscus- the curvature of a liquid surface in a solid container. • We measure the volume of a liquid at the bottom of the meniscus. • The SI unit for liquid volume is the Liter (L)= 1000 cm3. • Measuring a regular shaped solid results in a cubic unit. • Example: 3cm * 2cm* 1cm = 6cm3 • 1mL=1cm3=1cc
Mass- • Mass is the quantity of matter. • Even if something is smaller than another object, it can contain more mass if it is made of more matter. • Mass is a fundamental property of an object and does not change when a force is applied (i.e. gravity). • Mass is measured on a balance. • The SI unit of mass is the Kilogram (kg).
I’m not stepping on that scale… • Mass is not weight, but it is related. • Weight is the measure of gravity’s force on a mass. • F=ma, so Weight=mass times gravity’s acceleration. • Where gravity’s force changes, so does weight, but not the mass of an object. • http://www.exploratorium.edu/ronh/weight/
SystèmeInternationaled’Unités • The International System of Units or SI Units are units that have been agreed upon by scientists as the standard for measurements. • The metric system is the basis of the SI Units.
Oh metric system-you’re a perfect ten! • The metric system is a system of prefixes that utilize base ten to create scale. • This means, that converting between units within the metric system is as simple as moving a decimal point one direction or another. • -because numbers and place values are in base ten.
Converting to Metric- • Converting from the American/English measurement system to the metric system, and vice versa, requires a conversion factor and dimensional analysis. • The rules of dimensional analysis are easy • Start with the number and unit you are given (do not start with a conversion factor which usually looks like a fraction). • The units on top of a fraction must be canceled out by the same unit on the bottom of a fraction and the unit given MUST be canceled out first. • Apply conversion factors until every unit cancels except the unit you are looking for.
Example- • A recipe for French Boulaise calls for 5kg of beef. How many pounds of beef do you need to purchase if 2.2kg=1lbs? 2.27lbs
Measuring up…. • Measurements can be linked through common units and related equations. • Density is one property that can be used to ID a substance. • Density is the amount of mass in a given volume. • D=m/v, Density=mass/volume • Density has the SI units of g/mL
Example- • http://www.youtube.com/watch?v=hgnlu-kpdOs • The statue of gold that Indiana Jones steals by replacing the it with a bag of sand, presumably of the same mass, was approximately 1L in volume. The density of pure gold is 19.3g/mL. Sand has a density of 1.602g/mL. What volume, in L, of sand would Indiana Jones need to replace the statue without setting off the booby trap? 12.05L of sand