M easuring and U nits

The Dominion Mandate requires us to gain knowledge about God’s creation. To do so, we must take measurements. Measurement

measurement the act of comparing an unknown quantity to a standard unit

Types of Measurements Quantitative Uses numbers Qualitative Uses descriptions

27 meters milli Basic Unit Measurements Quantity Prefix

When you write a measurement … You must have a number. You must have a unit. You must have a number. You must have a unit. (How much information does the statement “I ran 7” give you?)

instrument a device to aid in measuring

Is accurately subdivided Is calibrated Instrument Has units on a scale

Quantitative or Qualitative 4 feet Extra large Hot 100 degrees F Sunny 96

Started with the metric system. Expanded to SI. SI System (International System of Units)

We will use 5 of these. There are 7 base units. SI System (International System of Units)

base units units that do not come from other units units that do not come from other units

Chemistry Base Units Length …………Meter (m) Mass ……………Kilogram (kg) Amount ………..Mole (mol) Time ……………Second (s) Temperature ….Kelvin (K) Length …………Meter (m) Mass ……………Kilogram (kg) Amount ………..Mole (mol) Time ……………Second (s) Temperature ….Kelvin (K)

derivative units units derived from base units Example: Volume derives from length. 1 cubic decimeter = 1 liter Example: Volume derives from length. 1 cubic decimeter = 1 liter

There are 22 derived SI units. 1 J = 1 kg. m 2 s 2 kg. m 2 s 2 Example: SI System

changing the units conversions

Conversions FACT: As the unit size gets larger, the number of those units needed becomes less.

milli centi deci deka hecto kilo ,000 mg 10,000 cg 1,000 dg 100 g 10 dag 1 hg 0.1 kg

Change 123,456.7 cm to km. kilo, hecto, deka, ---, deci, centi, milli smaller numbers larger units Centi to kilo moves 5 units to the left. Conversions

Change 123,456.7 cm to km. We must move the decimal 5 spaces to the left. 123,456.7 cm becomes km. Conversions

Convert 124 km to meters meters 2.12,400 meters 3.124,000 meters 4.1,240,000 meters meters 2.12,400 meters 3.124,000 meters 4.1,240,000 meters Question

mega kilo deci centi milli micro nano mega kilo deci centi milli micro nano

a tool used to solve problems in which units change a tool used to solve problems in which units change The Chemist’s Secret Weapon The Chemist’s Secret Weapon unit conversion

Example: Change grams to tons. Example: Change feet/sec to miles/hr. Example: Change grams to tons. Example: Change feet/sec to miles/hr. Unit Conversion

When you multiply or divide numbers, do the same to their units also. Therefore, if the same unit is on the numerator and denominator, it “cancels out.” This is how we change units. When you multiply or divide numbers, do the same to their units also. Therefore, if the same unit is on the numerator and denominator, it “cancels out.” This is how we change units.

a statement that two quantities are equal conversion factor

Grid Method Given InformationConversion 1 Factor (if needed)

Usually written as a fraction Example: 1 dozen eggs = 12 eggs One dozen eggs 12 eggs One dozen eggs 12 eggs Conversion Factor

Unit Conversion Change 1234 mm to meters mm 1 cm 10 mm 1 dm 10 cm 1 m 10 dm = m

Convert 3625 cg to g cg 1 g 100 cg = g Unit Conversion

How many pounds does a 37.6 kg boy weigh if g is equal to one ounce? (1 lb is 16 ounces.) Unit Conversion

37.6 kg to lbs 1 lb 16 oz 1000 g 1 kg 37.6 kg 1 oz g = lbs = 82.9 lbs Unit Conversion

How many grams are in a beef patty that is 0.33 pounds? (1 oz is grams.) How many grams are in a beef patty that is 0.33 pounds? (1 oz is grams.) 0.33lb 16 oz 1 lb g 1 oz = 150 g = g Unit Conversion

Calculate the cost of gas on a round trip from San Francisco to Los Angeles. The car used gets 24 miles per gallon of gasoline. Gas is $3.09 per gallon. The distance between the cities is 403 miles (one way). Unit Conversion

806 miles 1 gal 24 miles $ gal = $ = $104 Unit Conversion

Convert 101 lbs to grams. 1.34,905 g g g g 5.45,813 g 1.34,905 g g g g 5.45,813 g Question