Added Young and Freedman v12 p21.86 solution

diff --git a/latex/problems/Young_and_Freedman_12/problem21.86.tex b/latex/problems/Young_and_Freedman_12/problem21.86.tex
index 35cbdfc0085d3cbf17e865131a782cb7da2717dc..515955ea46389a2b7548d3d1e46fab24b2d25445 100644 (file)
--- a/latex/problems/Young_and_Freedman_12/problem21.86.tex
+++ b/latex/problems/Young_and_Freedman_12/problem21.86.tex
@@ -14,7 +14,39 @@ charge must be given to the drop?
 \begin{solution}
 \begin{center}
 \begin{asy}
+import Mechanics;
+import ElectroMag;
 
+real u = 1cm;
+real L = 3;
+real dy = 1;
+int n=3;
+
+Charge q = aCharge((0,0)*u, q=1, L="$q$");
+Vector v = Velocity(q.center, L="$v$");
+Wire top_plate = Wire((0,0.5*dy)*u, (L,.5*dy)*u);
+Wire bottom_plate = Wire((0,-.5*dy)*u, (L,-.5*dy)*u);
+
+path p = q.center;
+real x;
+real y;
+for (int i=0; i<=100; i+= 1) {
+  x = q.center.x+L*i/n;
+  y = q.center.y+.4*dy*(x/L)**2;
+  p = p..((x,y)*u);
+}
+draw(p, grey);
+
+Vector E;
+for (int i=0; i<n; i+=1) { 
+  E = EField((L*(i+.5)/n, -.4*dy)*u, mag=.8*dy*u, dir=90, L="$E$");
+  E.draw();
+}
+
+top_plate.draw();
+bottom_plate.draw();
+v.draw();
+q.draw();
 \end{asy}
 \end{center}
 From the forces on the drop in each direction