Plz help

Erika visits the Grand Canyon with her family. When she shouts near the edge, she can hear her voice echo throughout the canyon. Which statement describes why Erika hears her echo?

c.

Explanation:

Based on the information it can be said that the statement that best describes why Erika hears her echo is that the sound waves reflected off the canyon walls. An Echo is a sound that is repeated because the sound waves bounce off an object in the right way that it is reflected back towards its place of origin. Which in this case would be back at Erika after reflecting off the Grand Canyon's walls.

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.