The speed of light in a vaccum is about 3.00 x10^8m/s to determine how many km a pulse from a lazer beam travels in exactly one hour

Distance = (speed) x (time)

Distance = (3 x 10⁸ meter/second) x (1 hour)

Distance = 3 x 10⁸  meter-hour per second

Distance = 3 x 10⁵ kilometer-hour per second

Hmmm.  That answer is perfectly correct and totally useless.  We have no idea how far one meter-hour per second is.  It's a unit we never use.  We'd better convert the answer to a unit of length that we use every day.

(3 x 10⁵ km-hour/sec) x (3,600 sec/hour) =

(3 x 10⁵ x 3,600)  (km-hour-sec/hour-sec) =

1.08 x 10⁹ km

THAT's it !  A pulse of light in vacuum travels 1.08 billion km in one hour.

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.