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Applied Physical Science Class #3 Objective: Converting metric length units, converting Metric to English, or English to Metric. Imagine you have a little sister (really little). She is just 3.0 feet tall. How many inches tall is she?
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Applied Physical Science Class #3 Objective: Converting metric length units, converting Metric to English, or English to Metric. Imagine you have a little sister (really little). She is just 3.0 feet tall. How many inches tall is she? Although you probably just “knew” that answer, this is how your mind “did the math”. Then you cancelled the units to “convert” the units to a new unit that was still EQUAL to the first quantity of three feet. • = 3.0 ft1 X • 12 inches1 ft
= 3.0 ft1 X • 12 inches1 ft A conversion factor used to change feet into inches. NOTE: the top value EQUALS the bottom, so this whole fraction is really the same as ONE. Our original measurement, the height of your sister
= 36 inches 3.0 ft1 X • 12 inches1 ft 3.0 feet = 36 inches. Equal is profound, let’s pause and discuss that equal sign.
Problem one You run a 400. meter race, how many centimeters is that? To do this you need to convert meters to centimeters. Do you know how many meters = how many centimeters? If you know an EQUALITY, you can make a conversion factor, and do the math.
Problem one You run a 400. meter race, how many centimeters is that? I remember that 100 cm = 1 meter. Let’s figure out how to start the math… What is our starting fraction?
400 meters 1 X What is our conversion factor?
100 cm • 1 m 400 meters 1 X = 4000 cm 400 m = 4000 cm. Equals! 400 = 4000
X • = Your starting measurement with units, Over 1 A conversion factor, with proper units: top + bottom Your answer
Get a partner and calculators. Grab APS Handout #2 Unit Conversions There are a set of equalities provided and you can make conversion factors as needed with them. Make sure they are always right side up and never upside down! Make sure the units cancel out. Let’s do the first 4 with partners, then we’ll work on some more complicated ones together.