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    {
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     "output_type": "stream",
     "text": [
      "2.1\n",
      "C:\\Anaconda3\\lib\\site-packages\\vpython/data/glow.2.1.min.js\n"
     ]
    },
    {
     "data": {
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   ],
   "source": [
    "from vpython import *\n",
    "\n",
    "scene.caption = \"\"\"Right button drag or Ctrl-drag to rotate \"camera\" to view scene.\n",
    "To zoom, drag with middle button or Alt/Option depressed, or use scroll wheel.\n",
    "  On a two-button mouse, middle is left + right.\n",
    "Touch screen: pinch/extend to zoom, swipe or two-finger rotate.\"\"\"\n",
    "\n",
    "scene.forward = vector(0,-.3,-1)\n",
    "\n",
    "G = 6.7e-11\n",
    "\n",
    "giant = sphere(pos=vector(-1e11,0,0), radius=2e10, color=color.red, \n",
    "                make_trail=True, trail_type='points', interval=10, retain=20)\n",
    "giant.mass = 2e30\n",
    "giant.p = vector(0, 0, -1e4) * giant.mass\n",
    "\n",
    "dwarf = sphere(pos=vector(1.5e11,0,0), radius=1e10, color=color.yellow,\n",
    "                make_trail=True, retain=40)\n",
    "dwarf.mass = 1e30\n",
    "dwarf.p = -giant.p\n",
    "\n",
    "dt = 1e5\n",
    "while True:\n",
    "    rate(200)\n",
    "\n",
    "    r = dwarf.pos - giant.pos\n",
    "    F = G * giant.mass * dwarf.mass * norm(r) / mag2(r)\n",
    "    giant.p = giant.p + F*dt\n",
    "    dwarf.p = dwarf.p - F*dt\n",
    "    giant.pos = giant.pos + (giant.p/giant.mass) * dt\n",
    "    dwarf.pos = dwarf.pos + (dwarf.p/dwarf.mass) * dt"
   ]
  },
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