Background Information: In this lab, the different positions of a battery powered toy car moving in one direction over time (Velocity) was measured and recorded. Time and distance were the two physical quantities measured in this lab. A stopwatch and a meter stick were used to measure the distance the toy car travelled in a specific amount of time. Once the data points were collected and plotted, the relationship between the points was found using a line of best fit, which was in the form of y=mx+b.
Experimental Design: The purpose of this lab was to determine the equation relating the position to time of a moving battery powered car. The independent variable was the time (measured in seconds, with a stopwatch) throughout which the toy car travelled and the dependent variable was the how far (measured in meters, with a meter stick) the toy car travelled (its position). The toy car remained constant throughout the experiment. The hypothesis was that as the time increases, the toy car will continue to move forward at a constant velocity linearly.
Methods:
The lab was carried out in a fairly wide area so the car could have enough room to move and so that the lab members and other members of the classroom would not step on the toy car or trip over it, both of which could result in injuries. After a long and wide enough area was cleared to carry out the lab, team members were assigned tasks to do during the lab; these tasks included a timer, a car starter, and two people who marked the car’s position. The toy car’s starting position was marked with masking tape and the car was turned on and hovered over the starting point. As the timer was started, the car was immediately placed on its starting position; the toy car started moving. Starting at 0 seconds (when the car started to move), for every second that passed, a piece of masking tape was taped to the ground

indicating the position of the toy car at that time. As the seconds were called out, two people taped the pieces of masking tape to the ground alternatively, until 7 seconds. After 7 seconds had passed, the distance (in meters) between the starting line and each piece of masking tape were measured and recorded. This procedure, shown below, was repeated two more times for trials 2 and 3.

1
1
3
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5
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Tape
Tape
2
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6
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Start
Start

Data Collection: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | Trials | 0 | 0.56 | 1.13 | 1.56 | 2.07 | 2.52 | 3.05 | Trials | 0 | 0.53 | 1.03 | 1.53 | 2.34 | 3.52 | 3.96 | Trails | 0 | 0.48 | 1.13 | 1.64 | 2.11 | 2.49 | 2.87 | Average | 0 | 0.52 | 1.10 | 1.58 | 2.17 | 2.84 | 3.29 |

Data Analysis:

Slope of the line of best fit is calculated as follows:
Start coordinate of the line of best fit = (0,0)
Coordinate line of best fit passes through at 8 seconds at approximately (6, 3.3) (3.3-0)/ (6-0) = 0.55 meters per second. A possible source of error in this lab included not having enough accuracy to put the tape down on the ground at exactly where the toy car was at a specific time (at 1, 2,3,4,5 and 6 seconds). This lack of accuracy was due to the lab participants not having a perfect reaction time. Assuming an error of 0.10 seconds on every position value collected, each position value would have to be decreased 0.07 seconds on every position value collected, each position value collected, each position value would have to be decreased by 0.07. This would change the average distance values (y-values) from 1-6 seconds: 0.45, 1.03, 1.51, 2.1, 2.77 and 3.22. By graphing these values and calculating a new line of best fit for them, the slope of the line of best fit for the fixed values would come to about ((3.2-0)/(6-0)) = 0.53 meters per second, using the same slope calculating procedure used to calculate the original slope (explained below the graph). Knowing the slope of the original data and the slope of the fixed data, the percent error would come to ((0.55-0.53)/(0.53*100)) = 3.77%.
Results and Conclusion: The purpose of this lab was to determine the relationship between the time the toy car travelled and the distance it travelled (speed). Since the car travelled in one direction, the velocity was the same as the speed. This was accomplished by measuring the distances (ranging from 0.48 meters to 3.96 meters) a toy car travelled between its starting point and 1 through 6 intervals. The data resulting from the effect of time (independent variable) on the car’s position (dependent variable) was plotted. A line of best fit was found and the relationship between time and position was acquired from the linear equation of the line of best fit, whose slope was 0.55 meters per second. This means that the distance the car travels will be 0.55 times the time it travels. Therefore, the hypothesis that as time increases, the toy car will continue to move forward at a constant velocity linearly was shown by the data. After graphing the data points, the slope of the line of best fit came to be 0.55 meters per second. A possible source of error in this lab included not having enough accuracy to put the tape down on the ground at exactly where the toy car was at a specific time. Also, although most minor errors (other than accuracy) were minimized due to three trials being completed, an even smaller margin or error could have been achieved with more trials. So, assuming that the toy car travelled 0.07 meters less than marked, the slope would be 0.53 meters per second instead of 0.55, yielding a 3.77% error.