(PLEASE HELP ME, I NEED THIS RETAKE FOR SCIENCE AND I HAVE TO GET CAUGHT UP BEFORE NEXT MONTH).

1. A person walks 3 kilometers in an hour, rests for an hour, and then walks 3 more kilometers in another hour. What is the average speed of the person over the 3 hours? INCLUDE your calculations and units.

2. A ship sails north for 2 hours, traveling a total of 15 miles. Then the ship turns south and travels 6 miles in an hour. If north is taken as the positive direction, what is the velocity of the ship? INCLUDE your calculations and units.

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.

the answer is the index of refraction of the second medium is higher. i just took the test.