Speed and Velocity



Speed and VelocityWhat is speed and how is it related to velocity?In everyday language the word "speed is used in many ways. You may have heard of the expressions "speed it up" or "watch out for the speed trap". If you have ever taken a trip, you are also probably familiar with the expressions "one-way trip" and "round trip". Traveling by any means of transportation involved familiarity with distances, times, speeds, and directions. Speed is the rate of change in an objects position. This change in position is called its displacement. A car traveling at a speed of 55 mph for an hour will have a displacement of 55 miles. Velocity is similar to speed but also includes direction. For example, if a car is traveling south at 55 mph then we can say the velocity is 55 mph south. Objectives Investigate the concepts of position, direction, speed, and velocity. Measure and graph distance versus time for an object moving at a constant speed. Interpret this relationship.Model and explain constant velocity.Using data from an investigation, create a coding program that alerts the user to when they are outside the bounds of a constant velocity. Determine the slope of a line. Create a coding program that provides a visual vector display for velocity.Represent data using encoding schemes.Materials and EquipmentData collection system//code.Node//code.Node CartMeasuring tapeSafetyFollow regular laboratory safety precautions. ProcedurePart 1 – Describing position and constant speed1.Clear off an area to be your track for the //code.Node cart. Use measuring tape to create a track that is 1 m in length. 2.Place the //code.Node into the //code.Node cart. 3.Select Sensor Data in SPARKvue.4.Connect the //code.Node to your device. 5.Select the Line Graph display and select Position on the y-axis, with Time on the x-axis.6. Put the cart just behind the 0 mark. Start collecting data and push your cart at a constant speed to the 1 m mark. Pause for five seconds. At the same rate of speed, pull your cart in reverse back to the starting line. Pause for 5 seconds then Stop recording data. Repeat 2 more times, for a total of 3 runs. 7. Save your data file naming it Position and Constant Speed, or according to your teacher's directions. Recreate your cleanest run on Graph 1. Make sure to title the x and y-axes and create your scale accordingly. 8.Start a new experiment and repeat steps 5 through 6, but this time move the cart at a faster constant speed.9.Save your data file naming it Position and Faster Constant Speed, or according to your teacher's directions. Recreate your cleanest run on Graph 2. Make sure to title the x and y-axes and create your scale accordingly. Part 2 – Position and Velocity1.Start a new experiment and choose both Cart Position and Cart Velocity. Disable all other sensors. 2.Select the Line Graph Display. You should have two graphs. One for Cart Position vs. Time and one for Cart Velocity vs. Time. 4.Put the cart just behind the 0 mark. Start collecting data and push your cart at a constant speed to the 1 m mark. Pause for five seconds. At the same rate of speed, pull your cart in reverse back to the starting line. Pause for 5 seconds then Stop recording data. 5.Save your data file naming it Position and Velocity, or according to your teacher's directions. You will need to refer to this data in the Questions and Analysis section of the lab. Part 3 – Blockly Coding Challenge: Constant Velocity AlarmConstant velocity requires both constant speed and constant direction. When motion remains at the same speed, the object does not move faster or slower. When the motion is in a straight line, meaning the path does not curve, it is moving in a constant direction. Your challenge is to create a program that alerts the driver if they are not moving at a constant velocity. Your velocity should fall between 0.1 to 0.2 m/s, otherwise the //code.Node will alert the driver. 1.Using a measuring tape, create a straight track that is 1 m in length. 2.Start a new experiment and choose the Line Graph Display.3.Select Cart Velocity as your input and disable all other sensors. 4.Choose what output/s you will use in your program to alert the driver when they are out of range.5.Use a graph of Velocity vs. Time to record your data and review how well you did staying in the set range. 6.Test your program and share with other groups when complete. Part 4 – Blockly Coding Challenge: Vector DisplayVelocity is a vector quantity. This means it is direction aware. We often use an arrow to represent velocity since the arrow can represent both the magnitude of the speed and direction. This type of arrow is called a vector. Using Blockly, create a program using the 5x5 LED array as an output to demonstrate the cart's velocity as you move the cart forward and in reverse.Data CollectionGraph 1: Position and constant speedGraph 2: Position at faster constant speedQuestions and AnalysisPart 1 – Describing position and constant speed1.Using the data from Graph 1: Position and Constant Speed, compute the average speed of the cart. To do this, look at the portion of the graph where the cart was moving forward from 0 to 1 m. Determine the time it took for the cart to complete the 1 m track. Use the Coordinate tool to help you locate the data needed for the calculation. Use the space below to complete your work.average speed=total distance covered ÷time interval2. Using the data from Graph 2: Position and Faster Constant Speed, repeat the steps from Question 1. 3. How did the cart's speed change from Graph 1 to Graph 2?4. How can you tell from the position graphs where the cart's speed was 0 m/s?Part 2 – Position and Velocity 5.Using the Cart Velocity graph, the Linear Fit tool to determine the slope of the line moving forward. The slope of the line is the change in position over time, or velocity. Then determine the slope of the line moving in reverse. a.What was the slope of the line moving forward?b.What was the slope of the line moving in reverse?pare the forward and reverse velocity. Are they the same?6.Using your graphs of Position and Velocity versus Time. How can you tell from the velocity data when the cart's speed was 0 m/s? 7. Describe how can you tell from the velocity data which direction the cart was moving? 8. What is the difference between a velocity of 1 m/s and a velocity of -1 m/s? 9. How are the Cart Position vs Time graph and Cart Velocity vs. Time graph related?Part 3 – Blockly Coding Challenge: Constant Velocity Alarm10.What output/s did you select to alert the driver they were not moving at a constant speed? Did your program vary from others? If so, what was different?Part 4 – Blockly Coding Challenge: Velocity Vector Display11.What hardware block was needed to complete this challenge? Were you successful on your first try? If not, what challenges did you face? ................
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