1. Measurement of Acceleration due to gravity from a motion detector.
What did you measure?
We measured the position and velocity v time graphs from a falling basketball using a motion detector to get an acceleration.
How did you measure?
By using the program LoggerPro on the laptops we were able to setup a motion detector that was held by some rods to then detect a basketball that we used to drop right under the motion detector to achieve our results and data. We then fit the graphs with a quadratic curve fit to get our graphs.
What were your results?
After fitting our graphs with the quadratic curve fit we achieved two accelerations, on for the position v time and one for the velocity v time.
For position v time we got a value of -8.93m/s^2.
For the velocity v time graph we got a value of -9.416m/s^2
What was the standard deviation of your result?
We used other groups results to get a standard deviation of -9.500 +- 0.191m/s^2.
2. Measurement of acceleration due to gravity from Video Analysis.
What did we measure?
For this experiment we also measured some position v time and velocity v time graphs from a basketball being shot into the air and falling back down to get an acceleration.
How did we measure it?
This experiment was measured by performing a little test with shooting a ball into the air and watching as it fell back down while having a meterstick on the floor as my reference for length. I used a video analysis app to record and gather my data by plotting points for the ball in motion as well as setting an origin which was when the ball released from my hand. Then I fit them to quadratic and linear fits.
What were your results?For the position v time graph I used the quadratic fit and got -19.514m/s^2
For the Velocity v time graph I used the linear fit and got -18.14m/s^2
What was the standard deviation of your result?
Using the data of 5 other people I was able to get a value for the standard deviation. -9.183+-0.233m/s^2
3. Write-up on measurement variability.
%difference between the two experiments
Do your measurements agree within the uncertainty determined from the standard deviation?
The measurements in the motion detector and the video analysis don't agree perfectly with the uncertainty, although the one that was closer was the video analysis which had the closer uncertainty compared to the motion detector.
What measurements have uncertainty when using the motion detector?The measurement that have uncertainty when using the motion detector are the distance between the objects whether it be the motion detector and the ball or the ball and the floor as well as when the ball is dropped and how it is positioned or dropped.
What measurements have uncertainty when using video analysis?
Well with the experiment I did I think I was just supposed to drop the ball but I did something else with throwing it in the air and watching it come down which is probably why my values are doubled. But if I had just done the drop only some uncertainties would be kind of the same, how I decide to drop it as well as our cameras not catching the video perfectly or inconsistently setting points on the app.
Estimate the uncertainty for each of the measurements in the first and second experiments.
Motion detector value: -9.500 m/s^2土 0.191 m/s^2
Video analysis value: -9.183m/s^2 土 0.233m/s^2
Use the techniques discussed today to do uncertainty propagation for your measurements.
Do the measurements agree within your estimated uncertainty?
No the measurements do not agree within my estimated uncertainty.
Which of the measurements is more useful and why?
Although it seems like the video analysis did better I would say the motion detector since it has more of a chance to be accurate with less chances to interfere with causing uncertainties, I feel like more can go wrong with the video analysis than the motion detector as stated on how the measurements in each will cause uncertainties the video analysis seems to have more.
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