Lab # 4 Modeling the fall of an object falling with air resistance (Daniel Guzman)

Daniel Guzman

Lab#4: Modeling the fall of an object with air resistance

Physics 4A.



In this particular lab we were trying to understand and model the fall of different filter papers,, and how air resistance play a very important role on the filter papers motion as they were falling down.


The apparatus of this experiment consisted of a laptop, which has a very interesting software called logger pro. This particular software has many different tools to model different phenomena. In this particular experiment we used the tool called video capture, which was used to record the free fall of different filters, to then analyze them and extract valuable data to obtain the results desired.

The experimental procedure for this experiment was very simple, but very interesting, the first thing that needed to be done was to learn how to use logger pro's video capture due that the entire lab would depend on the videos recorded. Once the class knew how to use the video capture feature of logger pro the entire class went to the technology and design building were the lab took place. In this building the professor hang a black rough from a high of approximately 6 meters, so the filter papers would be easily seen  as they were falling. After the rough was hang we run a trial just to see if we were able to record appropriately the motion of a coffee filter . Once each was able to record correctly the motion of the coffee filter, the professor started telling us how many filters were going to be dropped at a time and the time at which he was going to release them. First, we recorded the motion of one filter paper and saved the video on logger pro immediately to proceed to the next trial were two coffee filter papers were dropped. This process was repeated until six coffee filter papers were dropped. Once all the videos were recorded and saved we had to scale any portion of the wall from which the filters were falling down, so the software would approximate what was the real distance that the objects traveled to obtain the position vs time graph.


Data and Graphs

How it was mentioned before once the scaling on the video is done one would obtain a position vs time graph which is very important because one can obtain the terminal velocity of the coffee filter by setting a linear fit on the graph and this would give us a slope which is the terminal velocity of the filter.

Here is shown the linear fit that is set on the graph and the slope of it is the terminal velocity of the coffee filter.

After the linear fit has been set for every single video one would obtain the terminal velocity for 1, 2 ,3 ,4, 5 and 6 filters. then one would find the force which is mg. then these is plotted in logger pro.

Plot a point for this plot is ignore in order to obtain a better correlation.

when we set a power fit on this plot we obtain the values we wanted to obtain. on this graph the values are A and B. Once these values are obtained f resistance can be found because all the other values are known.

Part 2.

Excel data tables to model the fall of the coffee filters. using values found in the first part (red)

filter paper #1

filter paper #2

filter paper # 3

filter paper 4 was skipped, video recorded wrongly

filter paper #5

filter paper #6

comparing results and discussion

The results obtained when modeling it in excel using the values from part one were good for some of the filters the terminal velocities were somehow close enough, the percent errors range from 0.68 to 2.8, which lets one infer that there are some sources of error in the results. some of the sources of errors might come from using the wrong video with the wrong number of filter papers, which occurred to us so we had to eliminate a point. Nevertheless, i was very impressed when i obtained my final results because it was a very interesting a approach due that all we used was a video and we were able to come with a model that works and is somehow accurate when modeling the fall of an object, another interesting thing was that the only apparatus used was a computer with a very interesting software that provide one with really god tools to model different phenomena. the sources of error might come from using the wrong video, or miss calculating a values when using excel.