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Graphs of Motion: P-T, V-T, and A-T SEPTEMBER 12-15, 2014 What do we already know about graphing motion? We know how to draw and interpret position vs time (P-T) graphs Straight lines = Constant velocity / NO acceleration Positive slope v=+ Negative slope: v=- Zero slope: v=0 What do we already know about graphing motion? We know how to draw and interpret position vs time (P-T) graphs Curved v=+ a=+ lines = Accelerated motion v=a=+ v=+ a=- v=a=- Your motion graph Take a minute a look at your graph of motion … do you still think it is correct? If not, fix it! V-T graphs What do you think these mean? Think, Pair, Share Rules for V-T graphs • Horizontal lines: a = 0 v = +, a = 0 v = +, a = + v = +, a = - • Positive slopes: a = + • Negative slopes: a = • Lines above the x axis: v = + v = -, a = 0 v = -, a = + v = -, a = - • Lines below the x axis: v = - Test your Understanding Think about your answer, wait until I tell you, then show me the answer by holding up the correct number of fingers. Which runner(s) have the greatest speed? 1) A 2) C 3) B & D 4) E Test your Understanding Think about your answer, wait until I tell you, then show me the answer by holding up the correct number of fingers. Which runners are slowing down? 1) A 2) C 3) B & D 4) E 5) None of them Test your Understanding Think about your answer, wait until I tell you, then show me the answer by holding up the correct number of fingers. Which runners are changing direction? 1) A 2) C 3) D 4) E 5) None of them You Do: Interpreting V-T Graphs Use the graph of the motion of a toy train, below, to answer the questions. 1) When is the train’s speed constant? From B-C, from D-E, and from F-G 2) When was the train’s velocity positive? Always! 3) When is the train’s acceleration positive? From A-B, from C-D, and from G-H 4) When did the train slow down? From E-F Putting it all together: Creating V-T and A-T graphs To create a V-T graph, I will first determine the v and a of each segment of the graph. v=+ a=- v=0 a=0 v=+ a=0 v=0 a=0 v=+ a=+ v=+ a=+ v=+ a=0 v=a=0 v=a=0 v=+ a=- Putting it all together: Creating V-T and A-T graphs v=+ a=- v=0 a=0 a=+ a=0 a=- v=+ a=0 v=0 a=0 v=+ a=+ v=+ a=+ v=+ a=0 v=a=0 v=a=0 v=+ a=- Creating V-T and A-T graphs: Testing your understanding Study the problem, then when I say, show “thumbs up” or “thumbs down” to indicate whether the graph has been drawn correctly. Creating V-T and A-T graphs: Testing your understanding Study the problem, then when I say, show “thumbs up” or “thumbs down” to indicate whether the graph has been drawn correctly. Creating V-T and A-T graphs: You Do Draw the corresponding V-T and A-T Homework HW sheet, HW Quiz next class Closure What were our objectives & how did we meet them? How did what we did today reflect our unit goal? How did we utilize our LP trait of communicators? What was our primary ‘way of knowing’ used today? Exit Ticket Complete motion graphs classwork sheet