Final answer:
The train operator should first stop the train if a car develops a grounded shoe beam. Tollbooths have wires to discharge static electricity from vehicles. Grounding an object allows it to lose its charge by dispersing it into the earth.
Step-by-step explanation:
When a train operator discovers a car has developed a grounded shoe beam, the first action they should take is to immediately stop the train to prevent any possible safety hazards. A grounded shoe beam can pose significant risks, including electrical hazards and potential for fires. The reason tollbooth stations have a piece of wire stuck in the pavement before them that touches cars is to discharge static electricity. This ensures that any static charge built up on the vehicle is safely grounded before it gets too close to the potentially flammable materials contained within the tollbooth area. When a second ball, such as in a static electricity experiment, is grounded while a charged rod is near it, it would lose its charge. This is because grounding provides a path for the charge to disperse into the earth, neutralizing the second ball.