For a well, the diameter of the potter's wheel at the head of the well is 0.4 meters. To lift the bucket from the water surface to the ground needs to rotate the potter's wheel 5 times. How many meters is the distance between the water surface and the ground?
一口井，井口上辘轳的直径是0.4米，把水桶从水面提到地面需要把辘轳转5周，水面和地面的距离是多少米？
<gadget id="calculator">3.14 * 0.4 * 5</gadget>
<output>6.28</output>

<result>6.28</result>