Motion Detector/Video Analysis Lab + Write Up

 1)  Measurement of acceleration due to gravity from a motion detector.

We measured the velocity and position of a basketball in freefall motion and used that data to calculate the acceleration due to gravity.

We measured by using a motion detector to track the basketball's position and velocity. The motion detector was mounted on a stand pointed at the ground roughly 5 feet in the air. We then dropped the ball below the motion detector so it was able to track the ball. All the data was captured through logger pro where graphs of both the velocity and position were provided and the necessary data we needed in order to do calculations. 

After doing calculations for acceleration, our group got  -9.22 m/s^2 using the data from position and -9.116 m/s^2 from the velocity data. 

What was the standard deviation of your result?

My result for standard deviation was 0.119

2) Measurement of acceleration due to gravity from Video Analysis.

For the video analysis, i dropped a small bouncy ball but used my phone camera to record and track the position and velocity using Vernier video analysis program. 

In order to find acceleration, I first recorded a video of the ball being dropped and a ruler on the same plane relative to the camera lens. Then I uploaded that video to the video analysis program. Using the plot points feature I was able to mark the position of the ball when in freefall for every frame of the video. Using that data and then scaling tool and the ruler placed next to the ball, I converted the pixels into meters and therefore resulted in a position and velocity graph in the correct units.

My results for acceleration from the position graph was -9.44 m/s^2 

My results for acceleration from the velocity graph was -9.45 m/s^2 

What was the standard deviation of your result?

My result for standard deviation was 0.461

3) Write-up on measurement variability.

(9.22 - 9.45) / 9.335 = 0.0247 x 100 = 2.47%

The percent difference between my two result was 2.47%

Yes, my measurements do agree with the uncertainties. 9.22 ± 0.119 and 9.45 ± 0.416

Factors such as faulty sensors or software and the angle at which the detector is positioned can both introduce errors. Reflections or interference from nearby objects may also affect accuracy.

Measurements that have uncertainty when using video analysis include data point plotting, scaling, camera parallax.

Yes, my measurements fall between the allowed range of the estimated uncertainty.

Based on the data from both the video analysis and logger pro, the logger pro would be more useful as it yielded a smaller uncertainty. Meaning when using the logger pro, the data is more precise while video analysis introduced too much uncertainty due to human error.