Final answer:
The experiment Elena conducts with her Toyota Camry is most relevant to the study of classical mechanics, which is the branch of physics that studies the motion of objects and the forces acting on them.
Step-by-step explanation:
The experiment in which Elena fills up the gas tank on her Toyota Camry 40 times and records the miles per gallon for each fill-up relates to Classical mechanics. The experiment Elena conducts with her Toyota Camry is most relevant to the study of classical mechanics, which is the branch of physics that studies the motion of objects and the forces acting on them.
Classical mechanics is the branch of physics that studies the motion of objects and the forces acting on them, which includes the study of vehicles and their fuel efficiency. By collecting data on the miles per gallon of her car, Elena is studying the relationship between fuel consumption and distance traveled, which falls under classical mechanics.