Final answer:
If a live power line is on a vehicle, stay a safe distance away and do not attempt to touch or approach the vehicle. Instead, remain inside if you are in the affected car, and call emergency services for assistance.
Step-by-step explanation:
If you notice a live power line on top of a vehicle involved in an accident, the safest course of action is to remain a safe distance away and not approach the vehicle. The metal body of a car can act similarly to a Faraday cage, which means if you are inside the car, the electrical field from the live wire should not reach you. However, attempting to exit the vehicle or touch it from the outside could result in electrocution. Therefore, it is best to stay put and call for emergency services to handle the situation. They have the proper training and equipment to deal with such hazardous circumstances safely.
It is also important to use common sense and prior knowledge in such situations. Regardless of misconceptions about high-voltage power lines, an active wire poses an immediate threat. Additionally, be aware of the bystander effect; if you cannot help directly, make sure to notify authorities who can.