Measurement—A common language

MEASUREMENT—A COMMON LANGUAGEAll science measurements are the same around the whole world—no matter what the measurement used in everyday life!

REMEMBER THESE MEASUREMENTS?

COMMON SI PREFIXES

PREFIXES SYMBOL MEANINGKilo k 1,000

Hecto- h 100Deka- da 10Deci- d 0.1 (one-tenth)Centi- c 0.01 (one-hundredth)Milli- m 0.001 (one thousandth)

WHAT DOES “SI” MEAN?• “SI” stands for the International System of Units.• Scientists all over the world use this system so all science minds think

alike on the measurements----this saves lots of misunderstanding. This standard use of the SI system helps to avoid wrong communication/s.

LENGTH:• Length is the distance from one point to another.• Measured in kilometers for “looooong distances”. . . Like our mile/s.• There are 1,000 meters in a kilometer.• When measuring what we consider as “regular and ordinary” objects, we would

use the meter. A meter is about the distance from the floor to a doorknob.• Most students your age are 1.5 to 2 meters tall.• For smaller lengths we use centimeters. There are 100 cm ( abbreviation) in a

meter and there are 100 millimeters (mm) in a meter. There are 10 mm in each cm.

• BTW--You can convert distance from miles to kilometers by just multiplying the number of miles with 1.6 . . . . . . cool dude!!

MASS:• Mass is a measure of the amount of matter an object contains. . . . In

other words, how much “stuff” there is.• The basic unit of mass is the kilogram. (That is 1,000 grams). In lab we

used the gram because our balance beams cannot measure masses past 610 grams!

• We have even smaller units for mass than the gram. We have a milligramalso. There are 1,000 milligrams in one gramWe measure mass with a triple beam balance. That allows us to measure an unknown mass against a known mass.Mass is NOT measured against the pull of gravity whereas weight is.

VOLUME:• Volume is the amount of space an object takes up.• To find out the volume of a regular object we measure length, width, and

height. Then we multiply them together: L X W X H = volume (cm3)

• Liquids have volumes too. We use “liter” when measuring a liquid.• We can also find the volume of an irregularly shaped object. We use the

water immersion method. Fill, write the amount of water down, place the object into the water, take the measurement again and subtract the 1st number from the 2nd. That difference is the volume of the irregular object.

DENSITY• Density is a measure of how much mass is contained in a given volume.• Remember the heart that we divide in half. . . .the top forming a “M” and

the bottom forming a “V”. . .. ? Density = Mass / Volume• Density is really made up of 2 units so it is expressed as g/cm3. When

using a liquid: g/mL (mL already considers measurements in it’s volume).

• Remember when something is put into a liquid, it will float if it is LESS dense than the liquid. It will SINK if it is MORE dense than the liquid.

• When reading a table of densities, the higher the number, the MORE dense the object is.

• A metal is more dense than Styrofoam: -vs-

TIME:• The passing of events is a measurement of time.• Time uses the second (s) for the SI unit.• A millisecond is 1/1000th of a second.• The longer periods of time are measured in hours and minutes---thank

heavens! Who wants to multiply our 2 ½ hours into seconds?!?!??! That is 9,000 seconds!!!!

•

TEMPERATURE:• Temperature is the measure of how hot or cold something is. It really is

measuring how much heat is in an object.• In science we use the Kelvin scale. In labs, we use the Celsuis because

the Kelvin is very LARGE numbers.• Zero on the Kelvin scale (0 K) is actually -273 degrees Celsius.• The Kelvin scale is useful because it does not have any negative numbers

to complicate the calculations. See the comparison---------

CONVERSION FACTORS:• To convert one measurement to another, we must know the appropriate

conversion factor. A conversion factor is an equation that shows how two units of measurement are related.

• Most conversion factors can be found using google. . . .makes it easy, heh?

• Examples: • to change meters to feet, multiply the meters by 3.2808.

• To change gallons to liters, multiply the gallon by 3.7853.

• To change pounds to kilograms, multiply the pounds by 0.4536

• See---it CAN be done!!!

MEASUREMENTS:• Very necessary and useful!!• Remember your vocabulary so you can understand what units the test may

be asking you.• If you have any questions, bring them to class with you tomorrow and ask!!

Happy Studying and that is all folks!