Free Fall Lab---determination of g

This is my second lab about determining of g.For making the lab to be successful, our purpose was collecting the data about the position of the object and time, and we can analyse those data to figure out the acceleration of the object so that we can get the g.
The first step, we prepared the apparatus:
1.a ruler: to measure the position
2.a free-fall body: to be object
3.heavy tripod base with leveling screws
4.tape and spark generator: to point the position of the object each time
5.power support
6.computer: to calculate the data
So, after we finished preparation, we collection the position data about when object was falling.As the picture:

During the object was falling, the spark generator would spark a black point on the tape. And we measured the positions about those points by ruler.

One by one, we typed the positions data into computer and marked the ordered time.And we could use the computer to find the those distance between points by excel.

We created 5 columns like time, distance, position. mid-interval time, and mid-interval speed as the picture shows. Using the tool in excel, we got the data in short time.

Second step, we created a new sheet and made a new liner picture to record the situation of the object about distance and time, and then fixed it correctly.

After all, we should got the acceleration about falling object, so we created another sheet and made a chart about the Mid-interval speed and Mid- interval time. And we also fixing it, and the slope will be the g we want to get.

And then, we got the g is 953.

For making the research deeper, we got the g from other groups, and created a new chart for errors and uncertainty. We made a column to collect the g and we calculate the average. And then, we created two columns about average deviation standard deviation of the mean.