In traffic regulations, motor vehicles should slow down when passing through crosswalks, which is a traffic safety measure to ensure the safety of pedestrians and non-motor vehicles.

Let's analyze this problem from a concrete mathematical model. Assuming that the speed of motor vehicles is V, the width of crosswalk is W and the walking speed of pedestrians is P, when pedestrians cross crosswalk, motor vehicles need to stop before pedestrians cross crosswalk to ensure traffic safety. Therefore, the driving distance of motor vehicles must be less than or equal to the width w of crosswalk.

According to the above conditions, we can establish the following mathematical model:

Motor vehicle travel distance = crosswalk width-motor vehicle travel distance on crosswalk

Assuming that the driving distance of the motor vehicle on the crosswalk is x, then:

v * t - x = w

Where t is the time required for the motor vehicle to pass the crosswalk.

In order to ensure safety, we hope that the longer the T, the better. Therefore, we can express t as twice the time for pedestrians to cross the crosswalk, that is, t = 2 * (w/p), because pedestrians need to cross the crosswalk twice (once entering the crosswalk and once leaving the crosswalk).

Substituting the value of t into the above mathematical model, we can get:

v * (2 * (w / p)) - x = w

After simplification, we get:

x = w * ( 1 - v / p) / v

This mathematical model tells us that the driving distance of motor vehicles on crosswalks is related to the speed v of motor vehicles, the width w of crosswalks and the walking speed p of pedestrians. Especially when the speed v of the motor vehicle is close to the walking speed p of pedestrians, the driving distance of the motor vehicle on the crosswalk is the smallest, which means that the motor vehicle must slow down as soon as possible to ensure traffic safety.

Therefore, according to this mathematical model, when a motor vehicle passes through a crosswalk, the driver should slow down to ensure that pedestrians pass safely. This is not only a traffic rule, but also a civilized driving behavior.