A thin, horizontal copper rod is 1.43 m long and has a mass of 236 g. What is the minimum current in the rod that can cause it to float in a horizontal magnetic field of 0.546 T

The minimum current in the rod that can cause it to float 2.96 A.

Explanation:

Given;

length of the copper rod, L = 1.43 m

mass of the rod, m = 236 g = 0.236 kg

magnetic field, B = 0.546 T

The magnetic of the rod is given by;

Fm = BIL

The downward force on the rod is given by;

F = mg

For the rod to float, the difference in the two force will be zero;

BIL - mg = 0

BIL = mg

I = mg / BL

I = (0.236 x 9.8) / (0.546 x 1.43)

I = 2.96 A

Therefore, the minimum current in the rod that can cause it to float 2.96 A.

answer; /// i believe that the correct answer is (c)

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.