Picket Fence and Ball Drop Labs - Accuracy vs. Precision

Picket Fence Free Fall

Objective: Measure the acceleration of a freely falling body (g) using a Picket Fence and a Photo-gate. 

Preliminary Discussion:

If an object is moving with constant acceleration, the shape of its velocity vs. time graph is a quadratic curve. The acceleration of the picket fence will be the same as the initial velocity, whether you are dropping or throwing downwards. 

Procedure:

1. Fasten the Photo-gate to the stand and provide a soft surface for the picket fence to land on. 

2. Connect the Photo-gate to the Lab Analysis app

3. When ready, begin to collect data and drop the picket fence from the top of the Photo-gate. 

4. Repeat this step multiple times to fill out data table

5. Examine your graphs and the slope of your graphs. 

Data Graphs: 

Data Discussion:

It is hard to determine the exact value we should be looking for not knowing our exact value of gravity in our classroom. This lab's procedure was efficient and involved few errors. Since the gate was held steadily by the stand, there was little error when it came to accidental movement. 

Ball Drop 

Objectives: 

- Collect position, acceleration, and velocity and analyze the graphs of each.

- Determine the best fit for the graph data collected

- Determine the mean acceleration from the acceleration vs. time graph 

Preliminary Discussion:

Predictions:

1. Positive vs. Time

2. Velocity vs. Time

3. Acceleration vs. Time 

Procedure:

1. Connect the motion detector to the Logger Pro App.

2. Place the motion detector on the floor.

3. Toss the ball straight up above the motion detector and let it fall back down. Record the data while it is doing this. Be sure to move your hand out of the way after you release it. 

4. Examine your graphs.

Data Graphs: 

Data Discussion:

This lab was quite difficult to manage in terms of reducing error. The motion detector was on the floor and could have quite possibly picked up movement from its surroundings. There was no way of determining where to start/how high the ball would go and that most likely affected our data.

OVERALL ANALYSIS;

The goal of these two labs was to determine which method was more accurate/precise in finding the value of gravity, which is about 9.8 m/s/s.Of course, this process involves the presence of errors, leading us to discuss: which lab has fewer errors? After reviewing data from both the Picket Fence and Ball Drop lab, I have come to the conclusion that the Picket Fence lab is a better method of reaching the 9.8 m/s/s. The Picket Fence lab involved dropping the picket fence through a photo gate that is held steadily in place by a stand. Since all we have to do was drop the picket fence through the gate, there was very little error. The Ball Drop lab involved throwing a ball up above the motion detector. This lab has multiple systemic errors. The motion detector has to be placed on the floor and would pick up movement from the surroundings. Also, the motion detector would pick up the motion of our hands as we threw the ball up. When it comes to the ball itself, it was started at/thrown to different distances throughout the lab, affecting the data of the lab. 

CONCLUSION:

Both labs involved creative procedures and electronically gathered information. Though neither are more accurate than the other, the Picket Fence procedure/lab has less major errors than the Ball Drop lab due to its better procedure/materials.