lab 2 Free fall lab

Purpose: The purpose of this lab is to examine the validity of the statement: In the absence of all other external forces except gravity, a falling body will accelerate at 9.8 M/s^2.

  Free fall apparatus


This apparatus measures the speed at which an object falls.  A body with mass (m) is held  at the top by an electromagnet. When the body is dropped a spark generator records dots on a strip of paper every 1/60th of a second.














Although we were unable to use the free fall apparatus we did receive a strip of paper that contained dots created the apparatus.


This is the strip of paper we received, it contains light dots that were imprinted by the spark generator on the free fall apparatus. Each dot is exactly 1/60th of a second apart from each other. we took the strip and measured the distance from from the dots. After we recorded the distance we created an excel file.



These are the points we measured along with time, change in distance and velocity after we put them
on a excel file. To the right of the file we have our velocity vs time graph which shows velocity increasing as time increases.

Question analysis:
        We are able to get our acceleration from our graph by performing a linear fit to the graph with gives us the slope of the graph, the slope of the graph is the acceleration due to gravity.
   
      Once again we are able to get our acceleration from pour position vs. time graph by performing a linear fit to get the slope. The slope of the graph is the acceleration due to gravity.

    Our Acceleration due to gravity
y came out to be 940 cm/s^2 of 9.40 m/s^2.
To find out how off we were we take the Absolute value of Accepted- Actual, our value was .41 m/s^2 off from the original value.

     A possible reason for the error is that our drop was not long enough. We might also need more sophisticated equipment to get a closer reading

Part 2:
Errors and uncertainty.
After we derived a measurement for gravity we had to analyze the data from the entire class by combining the results of the 9 groups in the class on an excel spread sheet.

Here is a copy of our excel sheet, at the top right we have the actual value for gravity followed by the calculated values from our class and ending with the average of all ten.

After we found our average, we had to add a new row and find the deviation from mean by subtracting the class calculated values from the average one by one as shown in rows B2-B12.

 After we found our deviation from the mean we squared then all to find our standard deviation.








The pattern in the our calculated g's is that they are all close to the value of gravity, none of the values are way off.
The average of the values allows us to take one set value for the entire class to compare to our separate values to find our standard deviation.
    One thing that might account for the difference in our value from the other values is that we have different techniques for rounding, which accounts for a systematic error.

The part of this lab is for us to learn how to calculate how incorrect our answer is from the original value. We learned that in order to get a standard deviation we have to have all of our numbers positive. We can get all of our number to be positive by either placing absolute values around the subtraction from our calculated and original value. Another way to make all of our values positive square then all and the the square root them after.