Final answer:
A vehicle is considered overloaded if the driver's view is obstructed. A trailer bouncing slowly on a highway is likely to be nearly empty, as less weight allows for more bounce compared to a heavily loaded one.
Step-by-step explanation:
A vehicle is considered overloaded if the driver's view to the front and side is obstructed. Overloading can significantly impair a driver's ability to operate their vehicle safely. When a freight truck with a trailer on a highway is observed with its trailer bouncing up and down slowly, it is more likely that the trailer is nearly empty. A heavily loaded trailer would have less bounce because the weight would dampen the movement resulting from bumps and inconsistencies on the road surface. On the other hand, an empty trailer has less mass to resist the up and down movement, leading to more noticeable bouncing.