Here He Comes. C. You should note three buttons: "Run", "Erase Track", and "Reset". There is also a meter that shows the time elapsed.

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1 Physics S432 Motion Graphing Inquiry Here He Comes Introduction You have already seen how computers can collect data from the real world using detection equipment. Now you will see another way that the computer can be a useful scientific tool. Because much of physics is governed by simple equations, computers can be programmed to make calculations and use the results to animate objects so that they behave as they should in the real world. This is called a simulation. The simulation software that we will be using is called Interactive Physics. You will study several simulations of motion, answer questions, and obtain data just like in an actual experiment. Part I-- Intro. & Speed Racer A. Double-Click on the icon "Speed Racer Qualitative". You will see the Interactive Physics start-up screen. Click on it. B. You should now see Speed Racer's car on the screen and also Racer X's car (and just how could Speed Racer not know that Racer X was his brother? He only wore a mask, it's not that difficult!) C. You should note three buttons: "Run", "Erase Track", and "Reset". There is also a meter that shows the time elapsed. D. Click "Run" and watch the simulation. After 8 seconds have passed, click the mouse again and the simulation should pause. E. Now, click "Reset" and "Erase Track". Run the simulation to 8 seconds again. Stop but do not reset it! Look at the bottom of the window. You should see some boxes that look like the buttons on a VCR remote or a (Quick movie if you have a computer ). These buttons will also control the simulation and do a frame-by-frame advance or replay. Run Forward/Backward Frame-by-Frame Run the simulation several times forward, backward, and frame-by-frame until you feel comfortable controlling the simulation. 1. Compare the velocities of each car as they begin the race. 2. Which car ends up ahead at 8 seconds? Why do you think this happens? (use physics terms) 3. You observed the simulation for 8 seconds. What is the smallest observable time increment that the simulation displays? 1

2 4. The images or 'tracks' formed as the cars move along appear simultaneously. Determine the amount of time that passes between images. Is this amount of time always the same for any two consecutive images of either car? Part II - Speed Racer with Numbers and Graphs In this part, you will see how a simulation can provide meaningful data to be interpreted. Opening and closing the simulation A. Open the file "Speed Racer Quantitative". If you don't know how then follow these directions: - Move the mouse up to the word "File. Hold the mouse button down, drag the pointer down to "Close", and release the button. - Move the mouse up to "File" again. Now hold the button and drag down to the word that says "Open" then release. - A new box appears that asks you to select a file. Move the mouse over the words 'Speed Racer Quantitative' and double-click. If you cannot find this file, ask for help. B. You should now see the same situation as before, only now there are two new meters. One measures the position (displacement from zero) of Speed Racer and the other measures the displacement of Racer X. C. Run the simulation several times and observe each meter. When you are ready, measure the position of each car at.5 sec intervals and record on the given data table. D. Now you will make a graph of the data using the application "Graphical Analysis". Quit Interactive Physics and launch Graphical Analysis. E. Click on the data tables where you see labels and units then type in information for your data. Next, enter the data for Speed Racer in order. F. To put both racers on the same graph, click on Windows and pull down to New Data Set. Type in Racer X's data and it should appear on the same graph. G. Go to File and make a print out of the graph. By hand, draw in a smooth line to fit the relationship shown by each car's motion. 1. Describe any differences/similarities between the motion of the two cars as shown by the lines. 2. Are there any times where the two cars are at the same point. List the times and positions based on the data. 3. Between time 0 and 1 sec, determine the velocity of Speed racer. Is it constant? 2

3 4. Between time 0 and 1 sec, determine the velocity of Racer X. Is this constant? I 5. If the velocity isn't constant in #4, what have you actually measured? 6. Can you determine at what time these two cars have the same speed? Do so! Part III: Sunday Drive A. Open the Interactive Physics file "Sunday Drive 3". B. Use the meters given to take displacement and time data again. C. Use Graphical Analysis to make a graph of your data. Print the graph. 1. Is this car traveling at constant velocity or accelerating? How do you know. 2. Is the acceleration the same as Racer X or different? Explain. 3. How does the graph shape compare to the previous graphs? 4. Are the distances & times in this simulation reasonable? (that is could are real car do what is shown here?) 5. If the road were slick, what might happen to the car's acceleration? 6. If the road were slick, what might happen to the graph? 3

4 Physics S432 Motion Graphing Inquiry Name: Per: Part I 1.. Compare the velocities of each car as they begin the race. 2. Which car ends up ahead at 8 seconds? Why do you think this happens? (use physics terms) 3. You observed the simulation for 8 seconds. What is the smallest observable time increment that the simulation displays? 4. The images or 'tracks' formed as the cars move along appear simultaneously. Determine the amount of time that passes between images. Is this amount of time always the same for any two consecutive images of either car? Part II Data Table: Position S-R Position RX Position S-R Position RX 4

5 1. Describe any differences/similarities between the motion of the two cars as shown by the lines. 2. Are there any times where the two cars are at the same point. List the times and positions based on the data. 3. Between time 0 and 1 sec, determine the velocity of Speed Racer. Is it constant? (show work) 4. Between time 0 and 1 sec, determine the velocity of Racer X. Is this constant? (show work) 5. If the velocity isn't constant in #4, what have you actually measured? 6. Can you determine at what time these two cars have the same speed? Do so! Part III Data Table: Sunday Driver Sunday Driver 1. Is this car traveling at constant velocity or accelerating? How do you know. 5

6 2. Is the acceleration the same as Racer X or different? Explain. 3. How does the graph shape compare to the previous graphs? 4. Are the distances & times in this simulation reasonable? (that is could are real car do what is shown here?) Give numbers for your arguments. 5. If the road were slick, what might happen to the car's acceleration? 6. If the road were slick, what might happen to the graph? 6