Luc, who is 1.80 m tall and has a mass of 80 kg, is standing at the center of a playground merry-go-round with his arms extended, holding a 1.25 kg dumbbell in each hand. the merry-go-round can be modeled as a 80-cm-diameter disk with a mass of 20 kg. luc's body can be modeled as a uniform 40-cm-diameter cylinder with massless arms extending to hands that are 80 cm from his center. the merry-go-round is coasting at a steady 40 rpm just before luc brings his hands in to his chest such that the dumbells are located on the rotation axis. afterward, what is the angular velocity, in rpm, of the merry-go-round?

the answer is false

explanation:

c) up is the direction the magnetic force is acting on the charge.

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.