5-1.html

(commands used to create the animation above)

>    macro(palered=COLOR(RGB, 1, 0.5, 0.5)):
p1:=fieldplot([-y,x],x=-5..5,y=-5..5,grid=[8,8],arrows=thin,scaling=constrained,color=palered):
p2:=plot({seq([i*cos(t),i*sin(t),t=0..2*Pi],i=1..5)},color=black):
for i from 1 to 20 do
  tt:=i*Pi/10:
  p3[i]:=pointplot({seq([i*cos(tt),i*sin(tt)],i=1..5)},symbol=circle, color=blue):
end do:
anip3:=display(seq(p3[i],i=1..20),insequence=true):
display(p1,p2,anip3);

>