Controlled variables: 1. The lighting was kept constant during the complete test. No additional light sources were added throughout the experiment, nor were any light sources removed throughout the experiment. This minimized the errors involved with trying to read and record the indicated measurements on the ticker tape, as well as the ability to analyze the experiment. 2. The same person measured and recorded the height and length of the incline plane and level horizontal track to ensure consistency in the recording of data.
By having the same person read all of the measurements minimized the degree of uncertainty in position and angle of reading values. 3. The same person recorded all measuring values on the ticker tape to ensure consistency in the recording of data. By having the same person read all of the measurements minimized the degree of uncertainty in position and angle of reading values. 4. The spark timer was set to a frequency of 10Hz (10 dots/s).
This eliminated the possible random error that could have been associated with the recording of time if a person were to record the time, due to delays in reaction time. By having the consistency of the spark timer record the time values the total accuracy and precision for the experiment was increased. 5. There was no wind or abnormal air movements during the complete test. No doors were opened or closed during the experiment, nor were any windows opened or closed, ensuring that the results would not be affected from air currents pushing or angling the car.