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The math of Physics. Equations. d = v t. In physics, equations are used to show how different measured quantities are related Each letter in this equation represents a different quantity or variable d – distance (in meters, m) v - velocity (or speed) (in meters per sec, m/s)
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Equations d = v t • In physics, equations are used to show how different measured quantities are related • Each letter in this equation represents a different quantity or variable • d – distance (in meters, m) • v - velocity (or speed) (in meters per sec, m/s) • t – time (in seconds, s) • v and t are written next to each other, so that means they are multiplied together • d is all by itself on one side of the equal sign…… so this equation solves for d (distance) • written as a sentence ….“Distance is equal to speed multiplied by time”
Units • Units (or labels) need to be included with all quantities • How tall are you? • 60 • ???? • Quantities make no sense without UNITS!!!
Units behave like numbers! • Units behave like numbers • When a number is divided by itself, the number cancels out leaving a 1. • Any whole number can be written as a fraction with a 1 as the denominator
For any equation… • The Units must be the same on both sides of the equal sign Units on both sides of the equal sign are equal to ‘m’!!
Motion formula --- d = v t Do units agree on both sides of each of these equations???
Example Problem • A car travels at 5 m/s for 120 s. How far has the car travelled? • What are they asking for? • What do you have? • What equation is best? • Plug in and Solve!
Example Problem 2 • A runner travelled 400 m in 80 s, how fast was the runner?? • What are they asking for? • What do you have? • What equation is best?
Unit conversions • Conversion factors are used to cancel out unwanted units and acquire desired units • 1 yard = 3 feet • 150 ft = _______ yds • 1kg = 2.2 lbs • 50 kg = _____ lbs • 5280ft = 1 mi • 3000 ft = ________ mi
More unit conversions • 1 N = .22 lbs • 7 lbs. = ________ • 1 km = 0.6 mi • 10 km = _____________ mi
Metric Prefix conversions • Important ones • Milli • Centi • ….. Base • Kilo
Practice questions about Metric units • How many meters in a Kilometer? • How many centimeters in a meter? • How many millimeters in a meter? • How many grams in a kilogram? • 340 g = _________________ kg • 230 cm = _______________ m • 3.5 km = ________________ m • 4500 m = ________________ km
Visualizing Units • Activity in library after in class demo’s.