Final answer:
Tractor trailers have large blind spots that can cause other vehicles to disappear from the truck driver's view. These areas are often beside or behind the truck. A trailer that is bouncing slowly is likely heavily loaded, as the weight provides more stability than an empty one.
Step-by-step explanation:
Tractor trailers have extreme blind spots which can cause cars to disappear from their driver's view. Due to the large size of tractor trailers, there are significant areas around the truck where the driver has limited or no visibility. These areas are commonly referred to as "No-Zones." If a car is in one of these No-Zones, particularly on the sides or directly behind the truck, it can become invisible to the truck driver, raising the risk of a collision if the truck changes lanes or stops suddenly. For safety, it is essential that other drivers on the road stay out of these blind spots and make sure they can see the truck driver in the truck's mirrors.
If your car's headlights are turned on while observing the bounce of a trailer on the highway, you would likely notice the reflection of your headlights. If the trailer is bouncing up and down slowly, it's more indicative of a heavily loaded trailer. The weight adds stability, reducing the bounciness that would be seen with an empty or lightly loaded trailer, which would tend to bounce more violently due to being less grounded.