Friday, October 23, 2015

Unit Multipliers/Dimensional Analysis (Saxon) (Glencoe) Converting units by using using unit multipliers (which is dimensional analysis)

Compute mentally:

What are units? Units-- the words we attach to numbers. Examples: 3 feet10 inches 5 meters Denominate number -- the number Units -- the word

What are units? Write the units on your white board. 4 yards 8 miles per hour 5,280 feet

U.S. Customary System The basic units of measure we use for length are related in the following ways: 12 inches = 1 foot 3 feet = 1 yard 5,280 feet = 1 mile You should memorize these!

U.S. Customary System The basic units of measure we use for weight are related in the following ways: 16 ounces = 1 pound 2,000 pounds = 1 ton You should memorize these!

What happens if you multiply something by a fraction that equals 1?

What would number would make each fraction equal to 1?

Unit Multipliers

Unit Multipliers can be written two ways.

Using Unit Multipliers Unit multiplier Unit multiplier

5 ft12 in 1 1 ft Notice that the units “ft” cancel. Yes, you can think this through without a unit multiplier. “I know there are 12 inches in every foot, so if I have 5 feet I will have 5 times 12 inches. However, for this assignment, USE unit multipliers. And…SHOW YOUR WORK!!!!!!!!!!!! = 60 inches

Another example:

What if? What if we had used the unit multiplier with yards on the bottom? 420 ft 3 ft 1 1 yd = 1260 ft ft 1 yd

Your Turn on the White Board Use a unit multiplier to convert 72 inches to feet. Answer: 6 ft

Your Turn on the White Board Use a unit multiplier to convert 4.6 miles to feet. Answer: 24,288 ft

Your Turn on the White Board Use a unit multiplier to convert 4 tons to pounds. Answer: 8000 lb

Classwork Time Show your work with unit multipliers even if you can convert these in your head. x What you have (number and units) Units you have Units you desire 1