01-Mar-2015: Free Fall Lab

Purpose: To experimentially calculate a value for the acceleration of a free-falling object due to gravity and use some statistics for analyzing our collective data.

This apparatus, allows a free-fall body to fall a distance of 1.5m while a spark generator zaps it every 1/60th of a second leaving a mark on the spark sensitive paper that lines the column.

Each lab group then recieved a seperate ribbon of spark sensetive paper that was used for a trial.

Since we know gravity accelerates the falling object, the direction where the consecutive marks are getting farther apart is our direction of fall. Each group then located their 1st mark(origin, x0) and measured the displacement from each of their following marks to their 1st mark. Using excel we created columns for time, total distance fallen, displacement from point to point, mid-interval time, and mid-interval speed. We then plotted a graph of Mid-interval speed vs. Mit interval time and set up a liner fit which gave us our slope(experimental acceleration due to gravity in cm/s^2).

We then compared our expiremental value of gravity with the other nine lab groups. We listed the ten values of g in one column and underneath had excel calculate the average. In the second column we found each values deviation from the mean and in the third column we squared each groups deviation. Finally we calculated the average of the squared deviations and square rooted that value to find our standard deviation for our values of gravity.

Each groups calculated a seperate value of g with no observable pattern possibly due to random errors. However, if we as a class omit my groups value of g the deviation would have been much smaller because ours was the most outlying value. I believe this might have been caused by the spark generator not being set to exactly 1/60 of a second but something slightly less making each one of our points farther apart then they should have been. Taking a look at the class' average value of g (942cm/s^2) compared to the accepted value of g (981cm/s^2) our value is still quite low. This may be due to systematic errors such ar the free-fall body draging against the wires, ribbon or column or of the apparatus itself.