What will change the velocity of a periodic wave?

Changing the medium of the wave.

Explanation:

Hi, a Periodic wave is a wave with a repeating continuous pattern or cycle that the source produces.

They are determined by the properties of the medium. So, if we change the medium of the wave It´s velocity will change.

The mediums are distinguished by their properties - the material they are made of and the physical properties of that material such as the density, the temperature, the elasticity, etc.  

Feel free to ask for more if needed or if you did not understand something.

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.