On the first day, we just built a Basic Two-Motor NXT Car. My partner and I got had few slight problems with the Lego pieces, but we got it to work in the end. On the second day, we connected the battery to the car and then the whole thing to the computer. Our task for the second day was to test the car with a time and power we selected on the program called Labview. The program let us select time period we wanted the car to run for (ex. 1 or 2 seconds) and the power (25 or 50). As the car runs, the computer would show us exactly the distance it traveled, the number of turns, and the velocity, but we also had to measure the distance ourselves to see how close we got to the actual distance determined by the program. We had to do 3 trials with a certain time and power x 3 (so it was 9 trials in total). Another thing that we needed to know for the number of wheel turns was the circumference of the tire.

Circumference= π(diameter) = 0.18 meters

Before we could start the trials, we needed some thing: a ruler and tape. The ruler was used so we could measure the distance the car went each trial. The tape was to let us know where the car started from.

First set of trials:

Time: 2 seconds

Power: 50

Trial #                   Trial 1              Trial 2                Trial 3

Measured              0.35                    0.365                     0.362

Computer            0.355                   0.369                      0.3685

# of Turns            1.9722                 2.05                        2.0472

Velocity                0.1775                 0.1845                    0.18425

% Error                1.418%                1.089%                     1.78%

 

2nd set of trials:

Time: 3 seconds

Power: 25

Trial #                Trial 1              Trial 2               Trial 3

Measured            0.24                    0.235                    0.24

Computer           0.24                   0.2355                  0.2395

# of Turns           1.333                  1.3083                 1.33056

Velocity               0.08                   0.0785                  0.07983

% Error                0%                     0.212%                  0.208%

 

Last set of trials:

Time: 6 seconds

Power: 25

Trial #                 Trial 1                Trial 2                   Trial 3

Measured           0.454                     0.474                         0.47

Computer          0.4653                  0.475                         0.466

# of turns           2.575                   2.63889                    2.58889

Velocity             0.07725                 0.07916                    0.07766

% Error              2.071%                   0.211%                     0.855%

 

The percent error of our trials were pretty close. They varied from 0% to 2% which means that the measuring skills were good. We got really close to the distance determined by the computer almost every time. The reason why it could have been a little off was that the car would sometimes not run in a straight line which made it a little difficult to measure. I would move the car to a straight line once it had stopped and tried to get it as close as possible. Another reason why the percentage error could have been a bit off was because of the ruler. For some of the trials, the ruler was too short for the distance the car had gone so measuring could have gotten messy there. Overall, the percentage error for the trials were very close and we even got a review of what velocity, distance, and acceleration is.