1. Section 2: Standards of Measurement

2.  A standard is an exact quantity that people agree to use to compare measurements.  A standard is always exactly the same quantity when it is used anywhere in the world.

3.  A measurement is a way to describe the world using numbers.  For a measurement to make sense it must include a number and a unit.  The metric system of measurement is based on multiples of ten.

4.  In 1960, the International System of Units was developed as an improvement to the metric system of measurement.  This system is abbreviated SI form the French Le Systeme Internationale d’Unites.

5.  Each type SI measurement has a base unit  There are seven (7) base units used in the SI system of measurement. Quantity MeasuredUnitSymbol LengthMeterm MassKilogramkg TimeSeconds Electric currentAmpereA TemperaturekelvinK Amount of substanceMolemol Intensity of lightCandelacd

6.  The SI system is easy to use because it is based on multiples of ten.  A prefix is added to the name of the base unit to indicate how many multiples of ten it should include. PrefixSymbolValue Kilok1,000 Decid0.1 Centic0.01 Millim0.001 Microµ0.000 001 Nanon0.000 000 001

7.  What is science?  What is a standard?  What are the three (3) major categories of science?  Upon which numeric multiple is the metric system based?  How does science explain God?  Name the seven (7) base units in the SI system.  Identify three (3) ways of investigating the natural world.  How many nanoseconds are in 2 seconds of time?

8.  In science, the word length is used to describe the distance between two points.  Metric rulers and metersticks are commonly used to measure length.  A meterstick is a little bit longer than a yardstick.

9.  The unit you choose will depend on the object being measured.  By choosing the best unit, you can avoid very large or very small numbers.

10.  Volume is the amount of space an object fills.  The volume of a rectangular solid, such as a brick, is found by multiplying its length, width, and height (V=l x w x h).  Volume is expressed as a “cubic” amount.

11.  What is the volume of a 2m x 3m x4m moving truck?  Write the formula:(V= l x w x h)  Substitute given values:(V=2m x 3m x 4m)  Solve the equation:24m 3

12.  To measure the volume of a liquid, you first must know how much liquid the container can hold.  Liquid is commonly measured in liters and milliliters.  1 milliliter = 1 cm 3

13.  What is an independent variable?  Why is the dependent variable measured instead of the independent variable?  What is the volume of a brick that has a length of 20 cm, a width of 6 cm, and a height of 5 cm?  What are the most common units for expressing the volume of liquids?

14.  Mass is the measure of how much matter is in an object.  You can determine mass by using a balance.

15.  A triple-beam balance gets its name because it has three beams that allow you to move known masses along the beam.  Because a triple beam balance compares a known mass to an unknown mass it is unaffected by gravity. Unlike a spring scale which really measures weight, the triple beam balance gives a true measure of mass.

16.  Density is the amount of mass in one cubic unit of volume of an object.  Density = mass/volume  If two objects are the same size and one object has a greater mass, it also has a greater density.

17.  Suppose an object weight 15 g and has a volume of 5 cm 3. What is the density of the object?  Write the formula:D=m/v  Substitute given values:D=15 g/5 cm 3  Solve the equation:3 g/cm 3

18.  Scientists need to keep track of how long it takes something to happen.  The unit of time in the SI system is second.

19.  Commonly think of temperature as how hot/cold something is...  Three scales for measuring temperature A.Fahrenheit B.Celsius C.Kelvin

20.  Based on the temperature of the human body at 98.6º  Water freezes at 32º  Water boils at 212º

21.  Scientists use the Celsius scale to measure temperature.  Water freezes at 0ºC  Water boils at 100ºC  The scale is divided evenly into 100 degrees between freezing and boiling.

22.  SI for measuring temperature is kelvin (K).  0ºK is called absolute zero.  0ºK = -273ºC  Divisions on the Kelvin scale are the same as the Celsius scale.

23. Sharon used a push-machine to thrust a basketball and a volleyball across a football field. The volleyball went farther than the basketball 9 out of 10 times. 1. What is the IV? DV? Constant (controlled variables)? 2. What can Sharon conclude about the density of the basketball? Why? 3. What other measurements can Sharon take to support her conclusions?