Alexander Reyes
Lab Partners: Mike Flores & Mike
Lab Performed:9/14/16 & 9/19/16
Statement: Air resistance force encountered by an object is dependent on its speed, shape and material.
Theory/Introduction: F(resistance)= kv^n can model the force an object experiences when in free fall. Coffee filters will be dropped from a balcony in this experiment and will determine relationship between air resistance force and speed. Secondly, an excel spreadsheet will be created to model the fall of an object with air resistance and find its terminal velocity.
Experimental Procedure: For part one of the experiment we headed to the design technology building in order to video capture the free fall of 1, 2, 3, 4, and 5 coffee filters. Professor Wolf taped a meter stick to a black tarp and dropped 1, 2, 3, 4, and 5 coffee filters in front of the tarp from a balcony as i video recorded the free fall for each drop. For part two of this experiment an excel spreadsheet was made with the information found for part one in order to calculate the terminal velocity for the falling objects.
Graphs of Data: Below are graphs from the data that was retrieved using video capture. The data was found by scaling the one meter stick, and plotting points onto the coffee filter as it was in free fall motion until it hit the ground. For each coffee filter drop, i had to find its velocity by using the linear fit line in order to obtain the slop of all plotted points. Coffee Filter #1 velocity=1.338 m/s, coffee filter #2 velocity=1.671 m/s, coffee filter #3 velocity=2.57 m/s, coffee filter #4 velocity= 3.27 m/s, and coffee filter #5 velocity=3.926 m/s. Soon after finding all velocities, i had to multiply acceleration due to gravity(9.8 m/s^2) with the mass of 1, 2, 3, 4, and 5 coffee filters in order to find the force. Forces found are the following: .008722, .017444, .026166, .034888, and .04361 all in (kg*m)/s^2. Once all velocities and forces were obtained a graph was plotted using the values above in order to find k and n in the power law (F(resistance)=kv^n). According to the last graph below the value for k=0.007955 +/- .001130 and n= 1.248 +/- 0.1187
Measured Data: Below is an excel data table with all information from part 1. From the information gathered the terminal velocity of the free falling coffee filters appears to be at 1.07 m/s. Plugging information into F(resistance)=kv^n equation, i get F(resistance)=(.007955)(1.07)^(1.248)=.008655.
Conclusion:The k and n value for the power law were determined within this experiment by video capturing the free fall of 1, 2, 3, 4, and 5 coffee filters. By imputing the information from part 1 of the lab into an excel data table the terminal velocity was found and the air resistance force was obtained. Uncertainties could have occurred when plotting points on the coffee filters on video capture or not scaling the 1 meter stick appropriately , which could have slightly altered the k and n values in the formula.
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