Day 12 cp-galileo's ramp

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Day 12 cp-galileo's ramp

  1. 1. <ul><li>CP Physics </li></ul><ul><li>Good morning! </li></ul><ul><li>Please… </li></ul><ul><li>Take out your homework & put it on the side of your desk, to be checked </li></ul><ul><li>Take out your positive & negative acceleration graphs that you completed for homework, and answer the following warm-up questions: </li></ul><ul><ul><li>Looking at the negative acceleration graph: </li></ul></ul><ul><ul><ul><li>Compare the distance traveled for the 1 st second and 10 th second of the trip </li></ul></ul></ul><ul><ul><ul><li>Describe the velocity graph </li></ul></ul></ul><ul><ul><ul><li>What is the area under the velocity vs. time graph curve </li></ul></ul></ul><ul><li>**I will start checking warm up problems for completion so make sure you do it in a timely manner!** </li></ul>
  2. 2. Housekeeping <ul><li>½ day Friday, No class for periods 2, 4 on Wed 10/12 </li></ul><ul><li>HOT task will be 10/14 </li></ul><ul><li>Kinematic story assignment due 10/14: see website for assignment details </li></ul><ul><li>Quiz on Friday will cover everything we’ve covered in out motion unit </li></ul><ul><ul><li>Study homework </li></ul></ul><ul><ul><li>Use equation sheet </li></ul></ul><ul><ul><li>See more sample problems </li></ul></ul><ul><ul><li>I am available Wednesday after school for help </li></ul></ul>
  3. 3. Homework <ul><li>Practice 2C: Using Δx = ½(v i + v f )Δt </li></ul><ul><ul><li>21 m </li></ul></ul><ul><ul><li>18.8 m </li></ul></ul><ul><li>Practice 2D: using v f = v i + at & Δx = v i t + ½at 2 </li></ul><ul><ul><li>Vf = 9.9 m/s, Δx = 0.03 km </li></ul></ul><ul><ul><li>Vf = 19 m/s, Δx = 60 m </li></ul></ul><ul><li>Practice 2E: Using v f 2 = v i 2 + 2aΔx </li></ul><ul><ul><li>Vf = 2.51 m/s </li></ul></ul><ul><ul><li>a) 21 m/s, b) 16 m/s, c) 13 m/s </li></ul></ul>
  4. 4. Using Graphs to solve problems <ul><li>Create graphs to solve the following problems: </li></ul><ul><li>Heather & Matthew walk eastward with a speed of 1.5 m/s. If it takes them 5 minutes to walk to the store, how far have they walked? Create a velocity vs. time graph to solve this problem (hint: change units of time to seconds). </li></ul><ul><li>When Maggie applies the brakes of her car, the car slows uniformly from 15.0 m/s to 0 m/s in 2.50 seconds. Create a velocity vs. time graph to determine how many meters before a stop sign must she apply her brakes in order to stop at the stop sign. </li></ul><ul><li>An automobile with an initial velocity of 4.30 m/s accelerates uniformly at the rate of 3.0 m/s 2 for 5.0 seconds. Create a velocity vs. time graph to find the displacement. </li></ul><ul><li>With an average acceleration of -0.50 m/s 2 , how long will it take a cyclist to bring a bicycle with an initial speed of 13.5 m/s to come to a complete stop? How far does the cyclist travel to come to a complete stop? Create a velocity vs. time graph to solve the problem. </li></ul>Answer = 450 m Answer = 18.75 m Answer = 59 m Answers: t = 27 seconds, x = 182.3 m
  5. 5. <ul><li>Shown is the distance the ball traveled down the ramp in one-second intervals </li></ul><ul><ul><li>Do you notice any patterns? </li></ul></ul>
  6. 6. His ANALYSIS indicated a pattern. The TOTAL DISPLACEMENT traveled from the start increased by perfect squares of the time interval.
  7. 7. Let’s Graph This! <ul><li>Create and fill out a data table for t, x, v f </li></ul><ul><li>How do we find v f ??? </li></ul><ul><li>Create d vs. t and v vs. t graphs </li></ul>
  8. 8. Let’s Graph This! <ul><li>Known: Unknown: </li></ul><ul><li>We also know that… </li></ul>v = v i + v f 2 v = x i - x f t 0 1 4 9 16 25 36 t v i xi xf 0 2 4 6 8 10 12 v = x f  t 2v = v f t xf vf 0 1 2 3 4 5 6
  9. 9. Graph it! 0 1 4 9 16 25 36 0 2 4 6 8 10 12 What is the acceleration? t xf vf 0 1 2 3 4 5 6
  10. 10. <ul><li>A falling body accelerates uniformly : it picks up equal amounts of speed in equal tme intervals, so that if it falls from rest, it moves twice as fast after two seconds as it was moving after one second, and three times as fast after 3 seconds, etc. </li></ul>
  11. 11. x(t) <ul><li>X(t) tells us that x (displacement) is a function of time </li></ul><ul><ul><li>We use the expression </li></ul></ul><ul><ul><li>X(t) = x i + v i t + ½ at 2 </li></ul></ul><ul><ul><li>This can tell is the displacement of an object at any time, given the initial velocity & acceleration </li></ul></ul><ul><li>Example: Joe accelerated from 0.5 m/s at 2.5 m/s2 for 5.0 seconds. Write an expression that can be used to find Joe’s displacement in this time frame. </li></ul><ul><ul><li>X(t) = x i + 0.5t + 1.25t 2 (from t = 0s to t = 5.0 s) </li></ul></ul>
  12. 12. v(t) <ul><li>v(t) tells us that velocity is a function of time </li></ul><ul><ul><li>We use the expression </li></ul></ul><ul><ul><li>v(t) = v i + at </li></ul></ul><ul><ul><li>This can tell is the velocity of an object at any time, given the initial velocity & acceleration </li></ul></ul><ul><li>Example: Joe accelerated from 0.5 m/s at 2.5 m/s2 for 5.0 seconds. Write an expression that can be used to find Joe’s displacement in this time frame. </li></ul><ul><ul><li>v(t) = 0.5 + 2.5t (from t = 0s to t = 5.0 s) </li></ul></ul>
  13. 13. A Kinematic Story <ul><li>Use the sample story </li></ul><ul><li>Use Motion man simulation </li></ul><ul><li>Work on your kinematic story, calculations, & graphs for homework </li></ul>
  14. 14. Graphs of Motion <ul><li>A - acceleration (+) </li></ul><ul><li>B - constant velocity (+) </li></ul><ul><li>C - deceleration (+) </li></ul><ul><li>D - stationary </li></ul><ul><li>E - reverse acceleration (-) </li></ul><ul><li>F - reverse constant v (-) </li></ul><ul><li>G - reverse deceleration (-) </li></ul>. t t t x a ... . . . . . . . . . . . . . . . . . . . . . . ... . . . . . .. . . . . . . . . . ... . . . . . . . v
  15. 15. Graphs of Motion <ul><li>A - acceleration (+) </li></ul><ul><li>B - constant velocity (+) </li></ul><ul><li>C - deceleration (+) </li></ul><ul><li>D - stationary </li></ul><ul><li>E - reverse acceleration (-) </li></ul><ul><li>F - reverse constant v (-) </li></ul><ul><li>G - reverse deceleration (-) </li></ul>. t t t s a A B C D E F G ... . . . . . . . . . . . . . . . . . . . . . . ... . . . . . .. . . . . . . . . . ... . . . . . . . v

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