Day 9 h-Intro to Motion -per1
- 1. Good morning! Please… Take out your homework & put it to the side of your desk, to be checked Answer the warm-up question: Using the graph provided, describe the object’s motion for the following time intervals: 0-4 seconds 4-6 seconds 6-10 seconds 10-12 seconds
- 2. Physics in the news Grades See grades posted at front of room by end of class Show me work missing if you were absent last week Measurement lab grades are in your folders
- 3. Page 49 #11, 13, 14, 16, 19 11. Average velocity = 0 km/hr (xi = xf) average speed = 55.4 km/hr 13. a = 4.3 m/s 2 14. t = 5.3 s 16. a = -6.3 m/s 2 0.64 g’s 19. (a) a = 2.2 m/s 2 (b) 110 m
- 4. Constant velocity lab data analysis and discussion questions Both the tables and graphs should be produced on a separate sheet of paper Set up d vs. t graph and v vs. t graphs so that d vs. t is on top of v vs. t and the times line up Use a ruler Read directions completely! See graded measurement labs in your folders Make sure to always include units! Explain your answers thoroughly
- 6. VELOCITY is the SLOPE of a distance, position, or displacement vs. time graph.
- 7. What is the slope doing? CHANGING, INCREASING What is the velocity doing? CHANGING, INCREASING
- 9. Describe the acceleration during interval A. The acceleration or SLOPE is constant and positive. Describe the acceleration during interval B. The acceleration or SLOPE is ZERO. Describe the acceleration during interval C. The acceleration or SLOPE is constant and negative.
- 10. What is the acceleration(slope) doing? The acceleration is INCREASING!
- 11. We can produce velocity vs. time graphs, and acceleration vs. time graphs based on info from a distance vs. time graph! Stationary Object Distance vs. Time Velocity vs. Time Acceleration vs. Time Object with Constant Speed Distance vs. Time Velocity vs. Time Acceleration vs. Time
- 12. We can produce velocity vs. time graphs, and acceleration vs. time graphs based on info from a distance vs. time graph! Distance vs. Time Velocity vs. Time Acceleration vs. Time
- 13. The slopes help us sketch the motion of other graphs! Graphs of an object moving with negative acceleration
- 14. LET’S REVIEW: We know that we can calculate the velocity of an object if given the displacement vs. time graph (find slope) We can also calculate the total displacement of an object if given the velocity vs. time graph This is done by finding the area under the curve
- 15. How FAR did this object travel during interval A? How FAR did this object travel during interval B? How FAR did this object travel during interval c?
- 16. The same thing can be done to find velocity, if given an acceleration vs. time graph Find the area under the curve.
- 17. v What is the change in Velocity during the t=2 to t=4 interval?
- 18. t (s) t (s) t (s) x (m) v (m/s) a (m/s/s) slope = v slope = a area = x area = v Graph Slope Area x vs. t Velocity N/A v vs. t Acceleration Displacement a vs. t N/A Velocity Slope Graph Area x vs. t v vs. t a vs. t
- 19. One of the more difficult applications of graphs in physics is when given a certain type of graph and asked to draw a different type of graph t (s) x (m) slope = v t (s) v (m/s) List 2 adjectives to describe the SLOPE or VELOCITY The slope is CONSTANT The slope is POSITIVE How could you translate what the SLOPE is doing on the graph ABOVE to the Y axis on the graph to the right?
- 20. t (s) x (m) t (s) v (m/s) 1 st line 2 nd line 3 rd line The slope is constant The slope is constant The slope is “+” The slope is “-” The slope is “0” Sketching a velocity vs. time graph given a distance vs. time graph This is IMPORTANT info you will need to do the lab analysis & graphing homework!
- 21. t (s) v (m/s) t (s) a (m/s/s) t (s) a (m/s/s) t (s) a (m/s/s) What is the SLOPE(a) doing? The slope is increasing
- 22. Lab data analysis & questions Create displacement vs. time and velocity vs. time graphs for problem 11 from your homework Graph so that d vs. t is on top, v vs. t is below it so that times line up Graph should show 3 segments: Segment 1: outgoing trip Segment 2: lunch Segment 3: return trip Use the v vs. t graph to calculate the total displacement of the trip, using the area under the curve.
- 23. Building a catapult! Will be done in groups of 3 Graded based on: Constructability Accuracy: hitting a target 10 meters away Due sometime at end of October: Date TBA A kinematic story: Write a story and create a d vs. t, v vs. t, and a vs. t graph to accompany your story Must have at least 5 trip segments within story Due next Tuesday, 10/4
- 25. Example: A boat moves slowly out of a marina (so as to not leave a wake) with a speed of 1.50 m/s. As soon as it passes the breakwater, leaving the marina, it throttles up and accelerates at 2.40 m/s/s . a) How fast is the boat moving after accelerating for 5 seconds? 13. 5 m/s What do I know? What do I want? v o = 1.50 m/s v = ? a = 2.40 m/s/s t = 5 s
- 26. b) How far did the boat travel during that time? 37.5 m
- 27. 1.5 m/s 13.5 m/s Total displacement = 7.50 + 30 = 37.5 m = Total AREA under the line.
- 28. Example: You are driving through town at 12 m/s when suddenly a ball rolls out in front of your car. You apply the brakes and begin decelerating at 3.5 m/s/s. How far do you travel before coming to a complete stop? 20.57 m What do I know? What do I want? v o = 12 m/s x = ? a = -3.5 m/s/s V = 0 m/s
- 29. I don ’t know which equation to choose!!! Equation Missing Variable x v t