To experiment is to repeat what you have observed again and again under controlled conditions and making an abstraction of the fundamentals: the cars are points which move and leave a trace.   Only one variable is modified at a time,  the independent variable, to see how it influences the phenomenon.  What is measured is the value of the dependent variable. The other variables, which are kept fixed are called controlled variables or control variables.
Here you have a simulation which allows you to vary the same parameter for the two cars. Experiment with the tracks of the cars concentrating on the fundamentals for your working hypothesis. Experiment and think! 

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