Coffee Filters and Air Resistance

Purpose: The purpose of the lab was to see a relationship between the air resistance force and speed of coffee dropping from a balcony.

For this experiment we used coffee filters, a 2 meter ruler, and video capture that was accessed through our lap top cameras. The coffee filters were used to measure the air resistance while the ruler was used as a scale when recording data from video capture. Video capture, overall, was used to get data from the coffee filters being dropped.

Procedure: First, we went over to the Design Technology Building in order to try and minimize the effect of drag when someone opens to door. One of us was then positioned atop of the balcony with the 2 meter ruler and the coffee filters while the other person was on the other side on top of the stairs recording the filter drop. We did this for 1, then 2 and all the way to 5 coffee filters on top of each other. We are doing this in order to find the terminal velocity which indicates that the gravitational force and the air resistance force equal each other.

The picture below shows the videos we captured during our data collection and the graph shows our data points acquired through the video capture. The slope near the end of the curve signifies the terminal velocity reached by each of the coffee filters. We need the terminal velocity in order to graph the Position vs Time. This process was done 5 times for each of the coffee filters used.

Below is the graph of Speed vs. Force that is used to determine k and n in the equation Air Resistance Force = kv^n. This graph was not used though because the third data point was really off.

Below is the new graph used for finding out the actual values of k and n. The third data point was not included because we thought we would get a better correlation if we excluded it. We got 0.007 for k and 1.793 for n.

Calculations: In order to verify that we were able to get the correct values, we plotted the values of k and n into excel in order to find the final velocity. The results proved to be the same so it was accurate.

Below are our calculations that we did for the experiments.

 Summary: First, we dropped the the coffee filter from the top of the balcony so that we could gather the data in order to find the terminal velocity. This was done by capturing videos of the filters falling. Then we found the final velocity by graphing the Position vs. Time for each of the coffee filters. Then we used the terminal velocities to graph the Speed vs. Force which gave us the k and n for the equation Air Resistance Force = kv^n. We then used Excel in order to verify our k and n values which proved to be correct. Overall, this lab proved to be successful since we came to the same results and there could be some uncertainty because interpreting the data can not be 100% accurate. All in all, the air resistance force is directly related to the speed as proved by the lab results.