\begin{problem*}{23.59}
A charged cork ball of mass $1.00\U{g}$ is suspended on a light string
-in the presence of a uniform electric field as shown in Figure P23.59.
+in the presence of a uniform electric field as shown in Figure~P23.59.
When $\vect{E}=(3.00\ihat+5.00\jhat)\E{5}\U{N/C}$, the ball is in
equilibrium at $\theta=37.0\dg$. Find \Part{a} the charge on the ball
and \Part{b} the tension in the string.
Charge a = pCharge((x,y));
-Vector T = Vector(a.center, mag=T_mag, dir=90+theta, "$T$");
+Vector T = Vector(a.center(), mag=T_mag, dir=90+theta, "$T$");
T.draw();
-Vector G = Vector(a.center, mag=G_mag, dir=-90, "$mg$");
+Vector G = Vector(a.center(), mag=G_mag, dir=-90, "$mg$");
G.draw();
-Vector E = Vector(a.center, mag=E_mag, dir=E_dir, "$F_E$");
+Vector E = Vector(a.center(), mag=E_mag, dir=E_dir, "$F_E$");
E.draw();
a.draw();