Final answer:
The slow bouncing movement of a freight truck's trailer on a highway suggests that it is likely to be nearly empty, due to the lack of weight to stabilize it compared to a heavily loaded trailer.
Step-by-step explanation:
When you pass a freight truck with a trailer on a highway, and notice that its trailer is bouncing up and down slowly, it usually indicates that the trailer is nearly empty. A heavily loaded trailer would have less bounce because the weight stabilizes it.
The suspension does not have to compensate as much for roadway irregularities. This observation is an application of the physics principle that heavier objects have a higher inertia, meaning they resist changes in motion more than lighter objects.
Similarly, pulling back lightly on the handlebar of a motorcycle leading to a left turn is due to countersteering, where the initial opposite force creates a lean to the left, thus resulting in the turn due to the bike's dynamics and the conservation of angular momentum.