Motion Detector/Video Analysis Lab

Motion Detector and Video Analysis Lab

Purpose:

To use LoggerPro and a Motion Detector to collect motion data, analyze errors, and model scientific data through graphical interpretation.

Measurement of acceleration due to gravity from a motion detector.

The measurements taken during the lab were the position and velocity versus time of a dropped ball. 

Procedure: 

1) Open LoggerPro and adjust the settings for the motion detector used for the lab. 

2) Mount the motion detector onto a pole so that the motion detector is far enough from the table so that the table would not be taken into account during the process of dropping the ball. 

3) Before dropping the ball, make sure your starting position is at least 0.2m away from the motion detector. 

4) Drop the basketball, while at the same time, have someone else push the collect button on LoggerPro to collect the data. 

5) Once you have collected the data, apply a curved or linear fit inside LoggerPro. 

6) Analyze the data and determine the acceleration due to gravity. 

Results: 

Position vs. Time:  x = -4.8t^2 + 7.7t -2.5

Velocity vs. Time: v = -9.61t + 7.7

From the collected data, the acceleration of the falling ball due to gravity was -9.61 m/s^2. 

Analysis: 

Motion Detector Standard Deviation: 0.152m/s^2

Measurement of acceleration due to gravity from Video Analysis.

Using the video analysis app, we measured the position and velocity versus time of a falling ball. 

Procedure: 

1) Set up a phone or camera so that the entire experiment is within the frame. 

2) Place a measuring device (meter stick, measuring tape, etc) inside the frame so that you are able to scale your measurements of the video. 

3) Hold the ball at whatever height, but high enough so that there is a bounce, and drop the ball. 

4) Using the video analysis app, import your video and adjust the settings. 

5) Frame by frame, track the ball at a consistent point to create your graphs. 

Results: 

Position vs. Time:  x = -4.82t^2 + 6.75t -2.81

Velocity vs. Time: v = -9.65t + 6.77

From the collected data, the acceleration of the falling ball due to gravity was -9.65 m/s^2. 

Analysis: 

Video Analysis Standard Deviation: 0.402m/s^2

Conclusion: 

The motion detector and video analysis measurements agree within uncertainty, as their acceleration difference of 0.04 m/s^2 is smaller than the 0.402 m/s^2 standard deviation of video analysis. The motion detector has a standard deviation of 0.152 m/s^2, making it a more precise tool. Uncertainty in motion detector measurements arises from sensor resolution, interference, and data fitting, while video analysis is affected by frame rate, tracking precision, and scaling errors. The estimated uncertainties are ±0.152 m/s^2 for the motion detector and ±0.402 m/s^2 for video analysis, confirming that the results align within these margins. The motion detector provides more accurate and consistent results due to its lower uncertainty. However, video analysis, despite its larger uncertainty, offers visual verification of motion, making it useful for analyzing multiple objects or confirming motion behavior. If high precision is required, the motion detector is preferable, but video analysis remains valuable for observational and educational purposes.