A 1.35-kg ball is tied to a 1.10-m long string is being spun in a vertical circle at a constant speed and with a period of 2.10 s. What is the maximum tension in the string?

T = 13.3 N

Explanation:

In this exercise we use Newton's second law, in the lower birth of the circle the tension and force are opposite, so the tension has its maximum value

          T - W = m a

The acceleration is centripetal

         a = v² / r = w² r

We replace

               T = mg + m w² r

The angular velocity is related to the period

              w = 2π f = 2π / T₀

             T₀ = 2.10 s

             T = m (g + 4π² r / T₀²)

Let's calculate

             T = 1.35 (9.8 + 4π² 1.10 /2.10²)

             T = 13.3 N

the force on the thing and the distance the force moves the thing

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.