In a cylindrical water bucket with a bottom radius of 30 cm, a piece of cylindrical steel with a radius of 10 cm is completely submerged in water. When the steel is taken out of the water, the water in the bucket drops by 5 cm. How long is this piece of steel?
在一只底面半径是30厘米的圆柱形水桶里，有一段半径为10cm的圆柱形钢材完全浸没在水中，当钢材取出水中时，桶里的水下降了5cm，这段钢材有多长？
<gadget id="calculator">30 ** 2</gadget>
<output>900</output>

<gadget id="calculator">3.14 * 900 * 5</gadget>
<output>14_130</output>

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

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

<gadget id="calculator">14_130 / 314</gadget>
<output>45</output>

<result>45</result>