cylindrical container with a base radius of 10 cm and a height of 40 cm contains water 38 cm deep. Now insert a cylindrical iron rod with a bottom diameter of 10cm and a height of 50cm vertically into the container. The bottom surface of the iron rod completely touches the bottom surface of the container. At this time, part of the water overflows. If the iron rod is taken out of the container again, how many centimeters does the height of the water drop from the height of the water before the iron rod was put in?
一个底面半径10cm，高40cm的圆柱形容器内盛有38cm深的水．现往容器内垂直插入一根底面直径10cm，高50cm的圆柱形铁棒，铁棒的底面完全接触到容器的底面，这时有一部分水溢出．如果再将铁棒从容器中取出，这时水面的高度比放入铁棒前的水面高度下降了多少厘米？
<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">5 ** 2</gadget>
<output>25</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">40 / 314</gadget>
<output>20/157 = around 0.127389</output>

<gadget id="calculator">3.14 * 25 * (20/157)</gadget>
<output>10</output>

<result>10</result>