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Speed and Velocity. Drag racing videohttp://www.youtube.com/watch?v=ryDYYGI1cwg. Speed. speed describes how quickly something moves. 4 different types of speed 1. instantaneous speed – how fast you are going at a certain point or time. example: radar gun or speedometer.
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Speed and Velocity Drag racing videohttp://www.youtube.com/watch?v=ryDYYGI1cwg
Speed • speed describes how quickly something moves. • 4 different types of speed 1. instantaneous speed– how fast you are going at a certain point or time. • example: radar gun or speedometer JSD- fastest speed through a photo gate
2. average speed – looks at the average speed between two points or times. • example: driving from Olympia to Seattle • what we will calculate in this class
3. constant speed– speed stays the same • example: cruise control • the slopeof a line is the ratio of the “rise” to the “run”.
Terminal speed (velocity) – the speed at which an object will stop accelerating when dropped • example: a sky-diver • Peregrine Falcon video http://www.youtube.com/watch?v=j3mTPEuFcWk&NR=1&feature=fvwp
They Might be Giants clip http://www.youtube.com/watch?v=DRb5PSxJerM Velocity • velocity is speed with direction (N, S, E, W, up, down, left, right) • positive when moving forward (to the right from an outside observer), and negative when moving backward (to the left to an outside observer). JSD– walk at constant speed and then change direction
Math for Velocity or Speed v = d/torv = d ÷ t v = velocity d = distance t = time • Unit of measurement is a distance unit over a time unit • cm/s, m/s, miles/hour, ft/year, miles/hour • if a velocity, should include direction (N, S, E, W)
5-Step Method to Solving Word Problems in Physical Science • Identify what you know (given) • Write down the correct formula to use • Show your work (“plug and chug” using calculator) • Write down answer • Make sure answer has a unit of measurement
Example problems • A bike travels 70 metersWest in 6.5 seconds. Calculate its velocity. • A car travels a distance of 100 miles in 2.2 hours. Calculate its speed. Given formula show work answer w/ units d=70m v=d/t t=6.5sec 70m/6.5sec 10.8 m/secWest Given formula show work answer w/ units d=100 miles v=d/t t=2.2 hours 100miles/2.2hours 45.5 miles/hour