x# = 150.0     :` starting position
m# = 10.0      :` mass
R# = 150       :` resting length
K# = 0.6       :` spring coefficient
v# = 0.0       :` velocity
f# = 0.9       :` friction
 
backdrop on
color backdrop 0
sync on
sync rate 60
 
dim points(12,1)
 
 
repeat
 
 
 
   if mousex() > x#-10 and mousex() < x#+10 and flag = 0 and mouseclick()
      mx# = mousex() - x#
      flag = 1
   endif
 
   if flag = 1 and mouseclick()
      x# = mousex() - mx#
   else
      flag = 0
      force# = -k# * (x#-R#)
      v# = (v# + force#/m#)*f#
      x# = x# + v#
   endif
 
 
 
   ink rgb(120,120,0),0
   box R#-10,230,R#+10,250
   ink rgb(255,255,255),0
   box x#-10,230,x#+10,250
 
 
   rem draw spring
   h# = (R#/x#)*20
   if h# > 20 then h# = 20
   offset = x#/12
 
   for t = 1 to 12
      if t mod 2 = 0
         y = h#
      else
         y = -h#
      endif
      points(t,0) = offset*t
      points(t,1) = 240+y
   next t
 
   line 0,240,points(1,0),points(1,1)
   for i = 1 to 12
      j = i+1
      if i = 12
         line points(i,0),points(i,1),x#,240
      else
         line points(i,0),points(i,1),points(j,0),points(j,1)
      endif
   next i
   rem end draw spring
 
 
 
 
   set cursor 0,0
   print "force: ",force#
   print "pos: ",x#
 
   sync
until spacekey()
 
end