A17-car train standing on the siding is started in motion by the train’s engine. 9 cm slack is between each of the cars, which are 9 m long. the engine is tightly connected to the first car and moves at a constant speed of 36 cm/s. how much time is required for the pulse to travel the length of the train? answer in units of s.

4 seconds

Explanation:

There are links between cars, they are in between

1-2, 2-3, 3-4, 4-5, 5-6, 6-7, 7-8, 8-9, 9-10, 10-11, 11-12, 12-13, 13-14, 14-15, 15-16, 16-17.

Here 1 represents the first car which is firmly attached to the engine. So, there are 16 links and each link has a slack of 9 m.

So, total slack

9×16 = 144 cm

Speed of train = 36 cm/s

Time taken by the pulse to travel the length of train is 4 seconds.

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.