Final answer:
Commercial vehicles with a gross weight over a specified limit are typically required to stop at weigh scales. A trailer bouncing up and down slowly on a highway is more likely to be nearly empty due to the decreased downward force. Exceeding the safety weight limit of a water taxi is a serious safety concern. Option (C)
Step-by-step explanation:
The question relates to commercial vehicles and their requirements for stopping at weight scales. Not all commercial vehicles need to report to weight scales, but there are specific criteria that determine when they must. Generally, the answer is c) Vehicles with a gross weight over a specified limit. This limit can vary by jurisdiction but is typically around 10,000 pounds. Therefore, not only trucks with trailers, but any commercial vehicle exceeding that gross weight must stop at the scales. This can include vehicles used for business purposes like delivery vans, construction vehicles, and others.
To address the physics aspect mentioned in the question, if a freight truck with a trailer is observed to be bouncing up and down slowly on a highway, it suggests that the load is not very heavy. A heavily loaded trailer would have less bounce due to the greater mass, which leads to more downward force and less susceptibility to the suspension's springiness. Therefore, it is more likely that the trailer is nearly empty if it is bouncing up and down more noticeably.
Considering part b of the question, if 20 men have a total weight greater than 3,500 pounds, it is definitely a safety concern. This is because the water taxi has a safety limit for a reason, which includes maintaining the vessel's stability and avoiding overloading which could lead to capsizing or other safety issues. Safety regulations are in place to prevent such dangerous situations, hence, exceeding the safety limits can pose serious risks.