1 / 77

Table of Contents

Table of Contents. Describing and Measuring Motion Slow Motion on Planet Earth Acceleration. Learning Objectives. Determine when an object is in motion. Key terms : reference point , relative motion, displacement Calculate an object’s speed and velocity.

borka
Télécharger la présentation

Table of Contents

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Table of Contents • Describing and Measuring Motion • Slow Motion on Planet Earth • Acceleration

  2. Learning Objectives • Determine when an object is in motion. • Key terms: reference point, relative motion, displacement • Calculate an object’s speed and velocity. • Key terms: average speed, instant speed, speed & direction, velocity • Demonstrate how to graph motion. • Key terms: slope = rise/run = rise divided by run = vertical movement divided by horizontal movement on a graph

  3. Graphing Motion Experiment (Part 1) • Goal- To create 4 distance vs. time graphs that correspond to the 4 below. Distance (d) is on the y-axis. • Background- What is your reference point for this experiment? (What are you measuring the distance from?) • Hypothesis- Describe how you think you will need to move for EACH of the 4distance-time graphs. 1 2 3 4 d (m) Time (s) Time (s) Time (s) Time (s)

  4. Graphing Motion Experiment (Part 1) • Results- Sketch your distance-time graphs and describe how you moved for each line segment of the graph. • Conclusion- In complete sentences and using the motion sensor as your reference point, describe how you would move (or not move) for… • A horizontal line on a distance-time graph. • A slanted line going down and to the right on a distance-time graph. • A curved line curving up and to the right on a distance-time graph. • What happens to the slope of the graph if a person moves faster? • What does the graph look like if a person is moving at a constant rate or speed?

  5. Learning Objectives • Determine when an object is in motion. • Key terms: reference point, relative motion, displacement • Calculate an object’s speed and velocity. • Key terms: average speed, instant speed, speed & direction, velocity • Demonstrate how to graph motion and how to interpret the graph. • Key terms: slope = rise/run = rise divided by run = vertical movement divided by horizontal movement on a graph

  6. - Describing and Measuring Motion Determining When an Object is in Motion • Have you ever watched a large truckpass you on the highway and felt like you were going backwards? • Whether or not an object is in motiondepends on the reference point you choose & if the distance between the object and the reference point is changing. Figure 2- Page 8

  7. Negative Distance & Football • Question: Can a distance be negative in relationship to a reference point? • Football Example: Reference point in football (below), positive play (right), negative play- sacked for a loss (bottom right)

  8. Which of the following is true if you are riding your bike past the middle school? • You are moving relative to the bike, but not the school. • You are not moving relative to the school or the bike. • You are moving relative to the school, but not relative to the bike. • You are moving relative to the bike and the school.

  9. Suppose you are driving, and you are pulled over by a cop. The cop explains that his radar gun measured you as going 30 mph in a 65 mph zone. He also tells you that he used his radar gun while driving down the highway. Using physics, how do you get out of getting a ticket for driving too slowly? • Explain that he graduated from Penns Valley. • Explain that since he was moving, your speed is relative to his speed. This makes it seem like you were driving slowly. • Explain that since he was moving, your speed is relative to his speed. This makes seem like you were driving fast. • Explain that you never drive slowly. You always drive fast.

  10. How would a position-time graph appear for an object at that is not moving? • A straight horizontal line • A slanted line moving up and to the right. • A curved line curving up and to the right. • A slanted line moving down and to the left.

  11. Which of the following distance-time graphs shows a person moving closer to a reference point? • Graph 1 • Graph 2 • Graph 3 • None of the graphs below. 1 2 3 d (m) Time (s) Time (s) Time (s)

  12. Which of the following shows a person moving at a constant rate? • Graph 1 only. • Graph 2 only. • Graph 3 only. • Graphs 1 & 2. • Graphs 1, 2, and 3. 1 2 3 d (m) Time (s) Time (s) Time (s)

  13. Which of the following shows a person moving the fastest away from the reference point? • Graph 1 • Graph 2 • Graph 3 • None of the above. 2 3 1 d (m) Time (s) Time (s) Time (s)

  14. - Describing and Measuring Motion Calculating Speed • What is an example of a speed that a fast car can go? • So, how can you calculate speed? If you travel 45 km in 3 hours, what is your average speed? • Speed = change in distance/change in time • Instant speed is your speed at a certain time. • Average speed is your averaged speed for the ENTIRE trial, event, or race. • Avg. speed = change in distance/change in time

  15. Speed vs. Velocity Experiment • Scenario (do not need to write): Markie is jogging at 6.0 mph, while Suzy is also jogging at 6.0 mph. However, Markie’s velocity is -6.0 mph while Suzy’s is 6.0 mph. Why are their speeds the same, but their velocities are different? • Goal: Determine the difference between SPEED and VELOCITY. • Hypothesis: What do you think is the difference between speed and velocity? • General Procedure (Handheld procedure done as a group beforehand): • Using the velocity-time graph’s (x,y) coordinates at the top of the graph screen, determine each person’s VELOCITY while moving away from the motion sensor. Be sure to check if the velocity is positive or negative. • Using the velocity-time graph’s (x,y) coordinates at the top of the graph screen, determine each person’s VELOCITY when moving back toward the motion sensor. Be sure to check if the velocity is positive or negative. • Results: Organize the VELOCITIES FOR EACH PERSON in a DATA TABLE.

  16. Speed vs. Velocity Experiment • Conclusion(answer in complete sentences): • Were there any negative velocities? Why is this the case? Is velocity just speed? If not, what else is factored in to velocity? Hint- Think about when your velocity was negative relative to the motion sensor, and keep in mind that speed is NEVER negative. • Scenario: Markie is jogging at a speed of 6.0 mph, while Suzy is also jogging at a speed of 6.0 mph. However, Markie’s velocity is -6.0 mph while Suzy’s is 6.0 mph. Why are their speeds the same, but their velocities are different? • Velocity = speed + direction relative to a reference point • So, Markie was going just as fast as Suzy, but in the opposite direction. Peregrine Falcons can dive at speeds up to 242 mph.

  17. - Describing and Measuring Motion Graphing Motion (Calculating speed) • You can show the motion of an object on a line graph in which you plot distance versus time. Remember: Velocity is the change in distance in a certain direction during a certain lengthof time. So, velocity or speed = rise/run

  18. Graphing Motion Experiment (Part 2) • In your lab notebook, match up each of the 4 distance-time graphs with one of the velocity graphs below. Sketch each of the graphs below and designate which velocity-time graph correspondsto which distance-time graph. • Useyour descriptions of speed or rate from Graphing Motion (Part 1) for help. • BE SURE TO CAREFULLY ANALYZE WHAT HAPPENED TO DISTANCE & DIRECTION AND WHAT IS HAPPENING TO VELOCITY FOR THE DURATION OF DATA COLLECTION TIME FRAME! V = velocity A B C D* V (m/s) Time (s)

  19. Graphing Motion Experiment (Parts 1 & 2) 1 2 3 4 d (m) Time (s) Time (s) Time (s) Time (s) A B D* C V (m/s) Time (s)

  20. Distance Determination (from a Speed-Time Graph) • How far will the object have gone in 2 seconds? • 10 meters (5 m/s x 2 s) • Or • Determine the area under the line: Create a rectangle and determine its area (l x w = 2 s x 5 m/s = 10 m) 5 m/s SPEED (m/s) 1 s 2 s Time (s)

  21. Jebediah runs 6 miles in 1 hour (60 minutes). His average speed is 6 mph. However, at minute 45, his speed was 4.5 mph. Which of the following would best explain what happened? • He was probably running faster at minute 45 than he was for most of the jog. • He got more energy from drinking 5 Red Bulls before jogging. • He was running up a hill and had to slow down. • He wore out his running shoes.

  22. Explain what happened between 0 and 4 minutes in terms of the person’s speed. Keep in mind, the graph is a DISTANCE-TIME graph. • The person moved at a constant speed • The person stopped moving. • The person slowed down. • The person moved faster.

  23. What is the velocity of the object based upon the data in the graph below? Assume time is in seconds. • 50 m/s • 10 m/s • 5 m/s • 50 m

  24. How is velocity different from speed? • Velocity involves instant and average speed, so it will be positive. • Speed involves direction as well, so it can be negative. • They’re the same. • Velocity involves direction as well, so it can be negative.

  25. Which of the following may only be a measurement of speed? • -0.001 mm/s • -2 m/s • 27 mph • 100 km/h East

  26. Which of the following is a measurement of velocity? • 32 rpm (revolutions per minute) clockwise • 100 km/h Northeast • -2.7 m/s • All of the above.

  27. Suzy is moving East at a velocity of 7 mph from her house. Markie moved 14 miles West from Suzy’s house in 2 hours. What is Markie’s velocity? • 7 mph • -7 mph • 6 mph East • -6 mph

  28. If you are running at 5 mph, then how far will you run in 4 hours at the same pace? • 25 miles • 5 mph • 20 miles • 15 miles

  29. How far will the object go in 4 seconds (using the graph below)? • 0 meters • 4 meters • 8 meters • 12 meters 2 m/s SPEED (m/s) 2 s 4 s 6 s Time (s)

  30. Noggin Knockers from p. 15- 1a, 1c, 2b, 2c, 3a, & 3b [9 points- Homework Grade] • 1- (a) Car- not moving • (b) Road- not moving since the distance between you and the road is not changing; • (c) Stop Sign- moving away or toward it. (1 point per part for 3 points total). • 2- Velocity = speed + direction (2 points) • 3-Slope and Speed = 600 meters/3 minutes = 200 m/min (2 points-1 point for the correct value, 1 point for the correct units). • 4- Distance = Speed x time = area under the line = 10 m/s x 3 s = 30 m (2 points- 1 point for value, 1 point for correct units)

  31. Softball vs. Baseball Reaction Times • Big Question: Is it tougher to hit a baseball than a softball? • Baseball data: • 95 mph fastball = 139.33 ft/.sec. • Distance from the pitcher’s mound = 60.5 ft. • Time it takes ball to get to the plate (t)= ? • Set up a proportion (t = time): 1 sec. / 139.33 ft. = t / 60.5 ft. • t = .434 seconds • *Note that it is slightly more time than the actual reaction time because the pitcher launches the ball about 5.5 feet in front of the mound! • Once this release point is taken into account, the reaction time is 0.395 seconds.

  32. Softball vs. Baseball Reaction Times • Big Question: Is it tougher to hit a baseball than a softball? • Softball data: • 72 mph softball = 105.6 ft/.sec. • Distance from the pitcher’s mound = 43 ft. • Time it takes ball to get to the plate (t)= ? • Set up a proportion (t = time): 1 sec. / 105.6 ft. = t / 43 ft. • t = .407 seconds • *Note that it is slightly more time than the actual reaction time because the pitcher launches the ball about 6 feet in front of the mound! • Once this release point is taken into account, the reaction time is 0.350 seconds.

  33. Graph Matching (No lab write-up) • Goal- Determine who can match the graph the best and how they were able to do it.

  34. End of Section:Describing and Measuring Motion

  35. - Slow Motion on Planet Earth Earth’s Plates • According to the theory of plate tectonics, Earth’s landmasses have changed position over time • because they are part of plates that are slowly moving.

  36. - Slow Motion on Planet Earth Plate Movement • Some plates move at a rate of several centimeters each year. Others move only a few millimeters per year.

  37. - Slow Motion on Planet Earth Continental Drift Activity • Click the Active Art button to open a browser window and access Active Art about continental drift.

  38. - Slow Motion on Planet Earth Previewing Visuals • Before you read, preview Figure 8. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions. Previewing Figure 8 Q. How have the positions of the continents changed over time? A. The distance between the continents has increased. Q. What causes Earth’s plates to move? A. Slow-moving currents beneath Earth’s outer layer cause the plates to move.

  39. End of Section:Slow Motion on Planet Earth

  40. Learning Objectives • Describe the motion of an object as it accelerates. • Key Terms: acceleration, change in velocity over time, increasing vs. decreasing speed, change in direction • Calculate acceleration. • Key Terms: change in velocity over time • Describe how graphs are used to analyze the motion of an accelerating object. • Key Terms: Velocity vs. Time graph, Distance vs. Time Graph, slope

  41. - Acceleration Calculating Acceleration • What does it mean if a car accelerates? Have you ever heard of a car that can go 0 to 60 mph in about 6 seconds? (Just like mine). What about when a car decelerates? • To determine the acceleration of an object moving in a straight line, you must calculate the change in velocity per unit of time • Average Acceleration = (final velocity – starting velocity)/time

  42. - Acceleration Graphing Acceleration • You can use both a speed-versus-time graph and a distance-versus-time graph to analyze the motion of an accelerating object.

  43. Velocity vs. Acceleration Experiment • Goal: Create the 3 velocity-time graphs below and determine which acceleration vs. time graphs they correspond to. Keep in mind that your graphs will be more rigid, but the general pattern should be the same. • Hypothesis: Determine how you think you should move for EACH of the 3 graphs (BY ONLY MOVING AWAY). • Results:Sketch your velocity-time graphs (hit the F2 button once and press up to adjust the scale), describe how you moved for each one, and match them up with the correct acceleration vs. time graphs. Use your descriptions for help. III I II V (m/s) Time (s) Time (s) Time (s)

  44. Velocity vs. Acceleration Experiment • Conclusion (answer in complete sentences): • How did you move for 0 or no acceleration? • How did you move for a constant positive acceleration? • How did you move for a constant negative acceleration (or deceleration)? • What is the independent or manipulated variable for the graphs above? What is the dependent or responding variable for the graphs above? Also, note which axis (x or y) the variables are on. A B A (m/s2) C 0 0 0 Time (s)

  45. Velocity vs. Acceleration Match-Up B A (m/s2) A C 0 0 0 Time (s) II I III V (m/s) Time (s) Time (s) Time (s)

  46. Learning Objectives • Describe the motion of an object as it accelerates. • Key Terms: acceleration, change in velocity over time, increasing vs. decreasing speed, change in direction • Calculate acceleration. • Key Terms: change in velocity over time • Describe how graphs are used to analyze the motion of an accelerating object. • Key Terms: Velocity vs. Time graph, Distance vs. Time Graph, slope

  47. - Acceleration Graphing Acceleration • You can use both a speed-versus-time graph and a distance-versus-time graph to analyze the motion of an accelerating object.

  48. - Acceleration Calculating Acceleration • To determine the acceleration of an object moving in a straight line, you must calculate the change in velocity per unit of time. • Average Acceleration = (final velocity – starting velocity)/time

  49. As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Read and Understand What information have you been given? Initial speed = 4 m/s Final Speed = 22 m/s Time = 3 s - Acceleration Calculating Acceleration

  50. As a roller-coaster car starts down a slope, its speed is 4 m/s. But 3 seconds later, at the bottom, its speed is 22 m/s. What is its average acceleration? Plan and Solve What quantity are you trying to calculate? The average acceleration of the roller-coaster car = __ What formula contains the given quantities and the unknown quantity? Acceleration = (Final speed – Initial speed)/Time Perform the calculation. Acceleration = (22 m/s – 4 m/s)/3 s = 18 m/s/3s Acceleration = 6 m/s2 The roller-coaster car’s average acceleration is 6 m/s2. This is a positive acceleration(speeding up). - Acceleration Calculating Acceleration

More Related