Air Resistance Physics 4A (8/17/16)

Physics 4A (8/17/16)

Air Resistance

Brett Mccausland

Lab Partner: Olivia Luphan

Purpose

Model the relationship between air resistance , force, and velocity, and analyze the velocity when the net force is 0 .

Procedure

We measured the mass of 250 coffe filters and then calculated the approximate mass of a single coffee filter. We then dropped coffe filters from a indoor balcony with a black sheet draped behind the path of the falling filter. On the black sheet we taped a meter stick in order to give a perspective of distance traveled. We made 6 separate recordings, the first recording with single coffee filter and with every recording we added 1 coffee filter.  

Calculations

We did some video analysis with logger pro by using the meter stick we had taped on the canvas to give logger pro the ability to have a perspective of distance then by marking the displacement of the coffee filter we gathered and plotted a displacement to time graph, using this  we found data on the falling filters velocities with use of the slope of the data points. We recorded the data from logger pro towards the end of the filters fall in order to capture its terminal velocity .

Next we modeled are force as a exponential function using a power fit, F= (k )( V)^n with V being terminal velocities. The graph to left illustrates this, the graph is force to velocity. Using excel and the data we found on terminal velocities,and  air resistance force we inserted in are data into excel and extend the calculations down over 60 rows or until we find the point in which the velocity stays constant, since we only had a limited distance for the filter to fall this allows us to find out had the filter had more distance to fall what would its final velocity be at the point in which the forces balance.  were able to find terminal velocities of the filters .

Conclusion and Data Analysis

The data in the excell spreadsheet models the falling object vey consistant with what is theorically known to be true.As can be seen on the excell sheet the change in velocity is continually decreaing and begins to level out as predicted. The graph seen in the excel sheet is based on a single coffee filter and as can be seen thru excel we have a calculated 2.5 m/s terminal velocity. Choosing to use the data from the first filter in hindsight was probably not a good decision since it gives us a higher propagation of error since the accuracy in the mass of the filter is an approximation based on 250 coffe filters. Also Of all the drops we made this drop was the most prone to be affected by external forces such as a breeze. Additionally even with the black canvas background, in many shots of are filming, it’s very difficult to make out the coffee filter, leading to error in marking are displacement in logger pro.