Name : ______Teacher initials: _____
Getting the speed of your constant speed geared car you made using a video and logger pro.
There will be various times when we will make/analyze short video clips of objects in motion. We make these short videos using our digital camcorders or iphones and then import them into Logger Pro. This software allows us to make a position-time graph and then determine how fast the object is going.
I’ve created a short movie, “Steps showing how to use loggerpro with video of your constant speed geared car you made.” To find the movie, go to http://media.usd497.org/. You might have to log on. Mouse to ‘media’ and click ‘albums.’ Find my album (2013_summer_school_science_videos_LHS) and then find the video. Make sure to watch this movie before starting.
1. .For this activity, you need to create a short video with your iphone or camcorder. You need to have a meterstick in your movie and film it in profile. DO NOT move your camera and stand back far enough so you can see the car move across the length of the meterstick. Make several movies in case one doesn't work out.
2. We will use Logger Pro to analyze it. The program should be on your school computer. Its icon is at the right.
3. Plug your iphone into USB port with a cable and make sure the it is not password protected.
4. Here are the correct steps:
- Open “Logger Pro” and run through the prompts if necessary.
- Mouse and click, “Insert, and mouse down to "movie."
- Find movie on your iphone or camcorder and click, "open."
- You should see the first frame of the video now. You may need to center it on your screen.
5. Right click on the movie and the open up, "movie options." Click on the, "First VA point defines movie time zero." and then click, "OK."
6. Once we have the video inserted, we can use Logger Pro to analyze the movie. At the bottom are some buttons like you might see on a CD player: play, fast forward, rewind, etc.
You can use these buttons to watch the movie clip or to find the position where you would like to start analyzing it.
7. Click the far right button( ) at the bottom in the movie player. This action will open up the video analysis tools, which appear on the right side of the movie player. A graph will also be displayed in the background (behind the movie player).
8. Make sure to scale the video using the “set scale” button, which is the fourth button from the top of the movie player on the right side. Now click and drag the mouse from one end of the meter stick to the other end. A pop-up dialog box will appear. The default of "1" for the Distance and "m" for the unit of measure is correct, so click OK. This is very important as it sets the scale for the video.
9. Next click the Forward Frame (next frame) button and advance the video so you see the buggy to the left of the meter stick.
10. Now click the Add Point button (second from the top). Move your mouse to the object you want to identify. Click the mouse once somewhere on the object you will always be able to spot. I like to use the front hubcap of the car. Notice that a dot is left on the screen, and the movie advances one frame. Mark the same spot on the object again (front hubcap) and repeat this process until you make about 20 dots. You do not have to go the full length of the meter stick.
11. When you have completed the analysis, you should see lots of dots on your movie player screen. Minimize this screen by making it tiny and move it away from the background graph. By default, the graph will display both the x and y positions versus time. For some activities, you will analyze the x position only (horizontal motion); for others you will want the y (vertical motion). To set that up, click the axis label [X(m) or Y(m)] of the graph and then click the axis you want to analyze. In this case, we want the X data. You should now only see the red dots which is the horizontal motion of the buggy.
12. Use your mouse and drag it over the most linear part of the points and then go to the next step.
13. This represents a position-time (or distance-time) graph. We know that a line means that the buggy or object is moving at a constant speed. We can get the speed and equation for your car by telling Logger Pro to get it for you. To do this, mouse up to analyze and then mouse to "Linear Fit."
14. You now have a box on the screen giving the slope and the equation. Here is an example:
15. The slope represents the speed of the geared car you made. On my example, I get its speed at 1.475 meters per second. Yours might be a bit different. What is your slope?
Your slope = your car's constant speed = ______meters per second
16. The equation X = mt + b represents the equation for the buggy. In physics notation:
distance = speed x (time) + b. For my example: distance = 1.475 x (time) - 0.3878.
17. Write down your equation here:
distance = ______(your slope) x (time) + ______(your b)
18. You can use your equation to help you find out how far the car might move in a given time. Let's say that we allow the buggy to move for 60 seconds (1 minute). Use your equation to determine how far (in meters) it would have moved:
distance = ______x (60) + ______= ______meters
NICE JOB, you just got the speed for the car you built!
adg, p. 1, Getting the speed of your constant speed geared car you made using a video and logger pro.