A boat crosses a 200m wide river at 3m/s ,north relative to water. the river flows at 1 m/s as shown . what is the velocity of the boat as observed on the river back from the boat departed

Explanation:

Given

Width of river

Velocity of boat w.r.t river

Velocity of river

Now using relative velocity concept

Suppose river is flowing towards east

so

and

So

So, boat appeared to be moving towards north-east

f=ma newton's second law 7x8=56n

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.