Workshop on investigate the kinematics of a falling ball Learning Physics of Sport Science through Video Analysis and Modeling, Anglo-Chinese Junior College, Singapore by Lee T.L., Wee, L. K. (2011, 19 January)

recently Tat Leong email the worksheet
https://docs.google.com/document/pub?id=1Qj4XBLEDT4jd-BH9KI80Fk4A-DVz46NGzzFG0SGOGF0
video can be doanloaded here http://www3.science.tamu.edu/cmse/videoanalysis/balldropbounce4x.avi
http://www3.science.tamu.edu/cmse/videoanalysis/  by Joel A. Bryan

 

not sure why the embed code result in a small window

Workshop to investigate the kinematics of a falling ball , Anglo-Chinese Junior College, Singapore by Lee T.L., Wee, L. K. (2011, 19 January)

Workshop on Learning Physics of Sport Science through Video Analysis and Modeling, Anglo-Chinese Junior College, Singapore by Lee T.L., Wee, L. K. (2011, 19 January)

recently Tat Leong email the worksheet
https://docs.google.com/document/pub?id=1Qj4XBLEDT4jd-BH9KI80Fk4A-DVz46NGzzFG0SGOGF0

Background:

Procedure:

1. Launch the software tracker by double clicking on the tracker.jar file.
2. Click the Open button 
3. Select the display of the clip settings by clicking the clip settings button at the bottom right end of the player as shown. 

4. Set the reference frame origin and angle. Click the Axes button .
5. To calibrate the scale on the video, click the Tape Measure button 

6. Click the Create button Point Mass.  

7. The ball maybe difficult to detect due to the quality of the frames, select the Video–Filters-Deinterlace-Even and close it after selection. This step may increase the visibility of the ball.

+ mouse click

8. If tracking an object, mark its position on every frame by holding down the shift key and clicking the mouse (crosshair cursor) as the video automatically steps through the video clip. Note: don't skip frames--if you do, velocities and accelerations cannot be determined.  Track the ball until end of frame. Plot and analyze the tracks The Plot View displays graphs of track data. To plot multiple graphs, click the Plots button and select the desired (3) plots number. Click the x- or y-axis label to change the variable plotted on that axis. In this video, choose y versus t, vy versus t & ay versus t.
9. Right-click on a plot (y versus t) to access display and analysis options in a popup menu. Select the various options as shown in the figure.

10. Select points you want to perform a curve fit. For this exercise,
    • select “Parabola” Fit Equation of the form y = a*t^2 + b*t + c,
    • select “Autofit”,
    • take a look at the parameters and values
11. Repeat Steps 9 to 11 for plot (vy versus t) and use the “Linear” Fit Equation y = a*t + b
12. Right click on the plot of vy versus t and select Analyze-Area and select by click and drag the 2 grey vertical boundaries to select the area to measure for the duration of start of motion to the start of 1st bound of the ball. Calculate the area under a velocity-time graph.

Drag the grey lines

13. Define potential energy, and total energy, via “data builder” (access through “Track Control”).

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Drag the grey lines

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FAQ: Video Analysis of a Falling Ball with Tracker Software

• What is the purpose of the video analysis workshop described in the document?
• This workshop aims to teach participants how to investigate the kinematics of a falling ball using video analysis and modeling techniques. It specifically utilizes the free software called "Tracker" to analyze the motion captured in a video, allowing for a deeper understanding of physics concepts such as speed, velocity, acceleration, and energy transformations.
• What software is used in this workshop and why?
• The workshop uses Tracker, a free video analysis software, as the primary tool. Tracker allows users to import video clips, calibrate the scale, track the position of objects over time, and plot various kinematic variables like position, velocity, and acceleration. This makes it ideal for visually analyzing motion in a way that is difficult to do with traditional methods.
• How does Tracker help in understanding kinematics?
• Tracker enables a visual and interactive approach to understanding kinematics. By tracking the position of a falling ball frame by frame, users can visualize the ball's trajectory and then generate plots of position vs. time, velocity vs. time, and acceleration vs. time. These graphs allow participants to directly observe and quantify the relationships between kinematic variables, for instance, how a constant acceleration affects velocity and position, and measure the acceleration due to gravity.
• What is the process for analyzing a video of a falling ball in Tracker?
• The process involves several key steps: first, the user imports a video and sets the start and end frames for analysis. Then, a reference frame is established and calibrated using a known distance in the video. Next, the position of the ball is tracked frame-by-frame, with the use of a deinterlace filter to improve the video quality if needed. Finally, the tracked data is used to generate graphs, which can be analyzed for kinematic variables and curve fitting, such as a parabola for position-time graph or a line for velocity-time graph.
• What kind of data can be extracted from the analysis using Tracker?

Using Tracker, you can extract detailed data including the ball's position in both x and y direction at each frame, from which it calculates the instantaneous velocity (vx and vy) and the acceleration (ax and ay). The tool is used to examine the change in position and the change in velocity in the y-direction for the falling ball. Additionally, Tracker is able to measure the area under the velocity time graph to calculate the displacement of the falling ball. Finally users can add data that can be used to examine potential energy, kinetic energy and total energy.

• How can you calculate the acceleration due to gravity using the Tracker analysis?

The acceleration due to gravity is extracted from the slope of the velocity time graph (vy vs. time) graph. After using Tracker to track a ball, a linear fit is applied to the vy vs t graph which will provide the slope of the linear line. This slope corresponds to the average acceleration of the ball, and if air resistance is negligible, it corresponds to acceleration due to gravity, which in this activity is in the vertical or y direction.

• Beyond kinematics, what other physics concepts can be explored using Tracker in this context?

While the focus of the workshop is on kinematics, Tracker can also be used to examine energy transformations. By defining and analyzing the potential and kinetic energies of the falling ball, you can visualize the conservation of mechanical energy, and analyze how potential energy gets converted to kinetic energy, and if applicable, the reverse.

• What additional resources are provided to support the learning process?
• The workshop materials include links to a sample video for analysis, a worksheet (Google Doc) that guides participants through the steps of the Tracker software, and links to tutorial videos on YouTube. Furthermore, there's also a link to a comprehensive help document that provides a deeper understanding of the software. These resources ensure a supported, effective and accessible learning experience for all the participants.