1.
when driving in rain the road becomes the most slippery:

just after the rain quits

right after it starts to rain

after it has rained for 20 minutes

when the wind is blowing at least 25 mph

When driving in rain, the road becomes the most slippery right after it starts to rain.

As the first rainwater hits the road, it mixes with the oil, rubber tire particles, and other gunk on the pavement, forming a very slippery coating on the surface.

After it has rained for a while, a lot of that gunk gets washed away, and most of the slipperiness is just water ... which is pretty slippery on its own, but not as slippery as it is when it has oil and rubber particles in it too.

russian is not my first language, so i'm afraid i can't write out an answer in russian, but hopefully you can find a way to do so. here's my best translation of the problem: you're given a plot of a particle's position in one-dimensional space over time, and you're asked to find either the total distance traveled by the particle after 6 seconds had elapsed, or the total displacement of the particle after 6 seconds.

if you want the total distance traveled, you would first need to determine the particle's velocity as a function of time, then integrate that over the 6-second interval. we know the position function is quadratic with roots at 0 and 6, so we have

where is unknown. because the position is parabolic, there is symmetry about the midpoint at , and we know that

so that the position function is

which means the velocity is

then the total distance traveled is

so the total distance traveled is 20 m.

on the other hand, if you want to find displacement: the particle starts at and ends at , so its displacement is 0.