The Metric System and Tools of Measurement

Why measure? Why use units? Invented so people could _________________ The ancient Greeks first developed the “FOOT (Hercule’s foot? King’s foot? Your foot?) The “YARD” was first developed for making clothes The “MILE” was developed by the Romans (The step of a Roman guard was about 2.5 feet; 1,000 double steps equaled one mile) Naturally, since everyone was different, much confusion ensued

The Metric System Base __________ system Based on a base unit that corresponds to a certain kind of measurement Length = __________ Volume = liter Mass = ___________ Temperature = Degrees Celsius (Kelvin) Time = seconds Weight = Newtons Prefixes plus a base unit make up a _____________ system unit. Example: Centi + meter = Centimeter Kilo + liter = Kiloliter

Basic Tools of Measurement _________ Metric Ruler/Meter Stick Graduated Cylinder ___________

Reading a balance: What is the mass of the small beaker located in your lab basket? Record that mass. Marble mass: ____________ ( )

Mass The measurement of the amount of __________ in an object Units: (SI): gram, Kilogram, milligram 1 gram 1 kilogram

Ruler and meter stick practice: Using a ruler, measure the length of the pencil found in your white container. Record your data. Pencil length: _________________ ( ) Using a meter stick, measure the length and width and height (from floor to top edge) of your table. Record this measurement. Table length: ___________ Table width: ___________ Table height: ___________

Distance An amount of ___________ between two things or people Units: (SI) - meter, kilometer, centimeter Examples: Meter -Width of a Door 1 Centimeter = Width of Your Finger 1 Kilometer = 365 Football Fields 1 Millimeter = width of pencil lead

Volume practice: Fill your graduated cylinder to the 25mL mark. Drop the marble into the cylinder (gently; do not splash). Record the new volume. V1= ________ ( ) Dump the water from the cylinder into your waste cup in order to retrieve your marble. Dry off your marble and place it back into your white container. Find the cylinder with colored liquid located at your table. Lift the cylinder above your nose, keeping your head still. Record the volume you see. V= ___________ ( ) Lower the cylinder below your nose, keeping your head still. Record the volume you see. V= ___________ ( )

curve in the surface of a liquid Meniscus curve in the surface of a liquid

Good measurements Read graduated cylinder at eye level Record volume at the bottom of the meniscus

The amount of _________ an object takes up Volume The amount of _________ an object takes up Units: (SI): liter, millimeter, cm3

Measuring Volume Solid Volume Measured with a ruler = Length x Width x Height (if definite shape) - Calculate the volume of your table. Show work: V= ___________ ( ) (if irregular shape) use the Water Displacement Method (with Graduated Cylinder) Use displacement to calculate the volume of your marble (V2-V1) Liquid Volume Use the Graduated Cylinder Measure from “bottom” of meniscus

Fill your larger beaker to the 50mL mark. Cylinder vs. Beaker Fill your larger beaker to the 50mL mark. Pour the water into a graduated cylinder. Record the volume. V= ________ ( ) Which piece of equipment do you think is more accurate?

Accuracy- How well a set of measurements _________ a given data set. Accuracy & Precision Accuracy- How well a set of measurements _________ a given data set. Precision- How _______ the measurements are within a set of data.

Accuracy and Precision Examples http://www8. nau

Name:_______________ Ticket Out of the Door In the Sports Center video, Drew Brees throws a football at a bulls eye. Are his throws accurate, precise, or both. Use your notes to support your answer.