25 Sep 2016 - Freefall Lab - Lab 2

Purpose: To test whether or not gravity on Earth accelerates objects at 9.8 m/s^2.
Apparatus: A 1.5m tall stand with a wire running along the entire height. There is a long, thin strip of paper that has marks "burned" on the from the wire at 60hz. at the top of the apparatus, there is a metal weight that is held up by an electromagnet. This metal weight is what causes the marks to be made at the paper. The position of the weight over the 1.5m drop is recorded at 60hz(1/60th of a second).
Theory: We are trying to measure the value of acceleration due to gravity on a falling object. The position of a falling object is recorded in exact time intervals of 1/60th of a second, and then was measured because it was imprinted on a 1.5m long strip of tape. We then plotted our points on a graph with the time on the x-axis and the change in distance on the y-axis. After this we then created a linear trendline and found the slope. The slope of the line gave us our value of gravity, as calculated using our measurements. The slope of a the line gives us our value of gravity because it shows acceleration. We know that the graph shows acceleration because if it was a constant speed with no acceleration, the line would have a slope of 0 and be flat.

Conclusions: Our value of gravity ended up being 9.2618 m/s^2, which was significantly off from the accepted value of gravity.
(9.81-9.2618/9.81)x100%=5.6% error
This error could have came from many sources, such as uncertainty as to the exact position of the falling object, because the marks on the paper were not perfect. Another source of error was human error in measuring the distances between the marks on the paper. One other source of possible error is that air resistance was not accounted for.
Questions:
1)if at t=0seconds v=1m/s; t=1 v=2; and t=2 v=3
the mid velocity is 2m/s
however, the average over the entire 2 second interval, is (3+1)/2=2m/s.
the mid-interval and average velocities are the same for constant acceleration.
2)
3)(already done above)

Part 2

1. The pattern of all the values from the class is that they are all very off from the accepted value.
2. The average value of the class is much lower than what is accepted.
3.All of the class values, except  for one, are lower than the accepted value of g. This is due to systematic error. Either the experiment used to test the value of g was not a very good one, or the apparatus could have been a source of error. Another likely reason for consistent lower values of g is that air resistance has not been accounted for. Air resistance opposes the force of gravity in this situation and could have been great enough to affect our values enough to effectively lower the values for the entire class.

Lab Partners were Elliot and Cesar.