In Arizona, severe drought conditions have often prompted officials to question whether the operation of public swimming pools should be permitted. As the chief engineer of the State of Arizona that has a large number of public pools, you have been asked to estimate the daily water loss due to pool evaporation. As representative conditions, you may assume water and ambient air temperatures of 30 oC, an ambient relative humidity of 10 %, pool surface dimensions of 6 m by 12 m, and a wind speed of 2 m/s in the direction of the long side of the pool. Assume the free stream turbulence of the air to be negligible and the surface of the water to be smooth and level with the pool deck. Estimate the water loss for the pool in kg/day.

measuring things 1 litre of water

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.