Set the piece of plastic or wood on the table and push it steadily across the tabletop using your fingertip. Note how much opposition to your push you feel. Repeat the steps, but this time push the piece of plastic or wood across a rug, carpet, or piece of fabric. If you’re using fabric, be sure to secure the fabric so it doesn’t move. How does the opposition to motion on the tabletop compare with that of the rug, carpet, or fabric? 20 points!

answer: what are you talking about?

explanation:

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it

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.