<p>If u have a any problems in physics , don't worry I will explain to u .</p>
<p>ANY problem ?</p>
<p>i am watching MIT physics lectures for SAT II .</p>
<p>Hmmm, OK, then, try this one:</p>
<p>A charge of +q moves toward the origin at velocity v along the x-axis. An identical charge moves toward the origin at velocity v along the y-axis. When the charges are at x=+1 m and y = +1m, respectively (it is assumed that the mass of each charge is large enough for no deviation of trajectory), the sum of all the electric and magnetic forces acting on both charges is:</p>
<p>A) kq^2 / 2, repulsive
B) kq^2 / 2, attractive
C) zero since Newton's Third Law says force on charge 1 = - (force on charge 2)
D) non-zero since Newton's Third Law doesn't work in this situation
E) proportional to q^2v^2/sqrt(2)</p>