+A particle having charge $q=+2.00\U{$\mu$C}$ and mass $m=0.0100\U{kg}$
+is connected to a string that is $L=1.50\U{m}$ long and tied to the
+pivot point $P$ in Figure~P25.7. The particle, string, and the pivot
+point all lie on a frictionless, horizontal table. The particle is
+released from rest when the string makes an angle $\theta=60.0\dg$
+with a uniform electric field of magnitude $E=300\U{V/m}$. Determine
+the speed of the particle when the string is parallel to the electric
+field.
+\begin{center}
+\begin{asy}
+import Mechanics;
+import ElectroMag;
+
+real u = 3cm;
+real theta = 60;
+pair a = u*dir(theta);
+pair b = (u, 0);
+
+Angle t = Angle(a, (0,0), b, "$\theta$"); t.draw();
+draw(a -- (0,0) -- b);
+dot("$P$", (0,0), align=W);
+Charge A = pCharge(a, Label("$m$", align=N)); A.draw();
+A.lc.draw_label(Label("$q$", align=E));
+A.lc.draw_label(Label("$v=0$", align=W));
+label("$L$", a/2, align=NW);
+
+Vector v = Velocity(b, mag=u/3, dir=-90, "$\vect{v}$"); v.draw();
+Charge B = pCharge(b); B.draw();
+Vector E = EField((0.7u,u/2), mag=u/3, "$\vect{E}$"); E.draw();
+
+label("Top view", (u/2, 0), align=S);
+\end{asy}
+\end{center}