Physics 4A Free Fall and Experimental Uncertainty

Physics 4A (8/31/16 )

Free Fall and Experimental Uncertainty

Brett Mccausland

Lab Partner: Olivia Luphan

Purpose

Find the constant acceleration of gravity through use of experimental data. Compare data and discover whether the experiment contains errors of the systematic nature or random error.

Procedure

We placed the cylinder onto an electromagnet at the top of the apparatus shown in the image and turned a  spark generator on just before releasing the cylinder.The cylinder contained a metal ring around its rubber base and this ring left burn marks on a piece of wax paper that was extended out from a spool at the bottom all the way to the top of the path of the falling cylinder.

Calculations

These marks on the wax paper provided us with a displacement and the sparker gave us a know time. Using this data we found velocity at each corresponding displacement by first finding a mid interval time. We  used the mid interval times to find a mid interval velocity which we then graphed on a velocity to time graph.The points on the graph made a linear graph as expected and with the use of a trim line we found the slope which gave us are acceleration.

Conclusion and Data Analysis

After comparing data from all the groups who were conducting the exact same experiment we found that we had a standard deviation of about 24 cm/s^2 .This however was with the use of an outlier point the was under the average deviation of the mean by approx 50 cm/s^2. We made the determination that this data was invalid and removed it from the calculations. After doing so this brought us to a standard deviation of about 16 cm/s^2.The remaining deviation in the data was not leaning toward any particular value, leading us to believe the experimental errors were random since the measurements were scattered.Of course we all know the theoretical value of gravity is estimated to be approximately 9.8 m/s^2 and the results were more scattered around 9.5 m/s^2. The theoretical value is what you would expect in a vacuum with no air resistance and are object encounters air resistance. The shape, mass, and low velocity of the object makes for near negligible air resistance however it still contributes to why we have a lesser calculation for  g.