Final answer:
A driver towing a trailer keeps to the right on a three-lane highway to comply with traffic regulations, enhance safety, and manage the physical aspects of towing a trailer, such as controlling sway according to Newton's first law of motion.
Step-by-step explanation:
On a three-lane highway, a driver towing a trailer keeps to the right while driving for several reasons which can be related to traffic regulations, safety, and physics. In many regions, slower moving vehicles are required by law to stay in the right-hand lanes, while the leftmost lanes are reserved for passing or faster-moving traffic. This helps to maintain the flow of traffic and reduces the likelihood of accidents caused by faster vehicles having to frequently change lanes to overtake slower ones.
From a safety perspective, trailers can be more challenging to maneuver and have a longer stopping distance, making it safer to travel in the right-hand lanes where they are less likely to require sudden lane changes. Additionally, keeping to the right is a precaution against the trailer's tendency to sway, which can be more easily controlled at lower speeds and in the right lanes where there's typically more room for correction.
Newton's first law of motion can also explain why trailers must be handled carefully on highways. According to this law, an object in motion will remain in motion unless acted upon by a force. When a trailer begins to sway, it wants to continue doing so due to its inertia. Driving at slower speeds in the right-hand lanes allows the driver more reaction time and control to counteract this swaying motion and restore stability to the vehicle and trailer combo.