A rectangle is 4 cm long and 2 cm wide. What is the volume of the three-dimensional figure obtained after rotating the rectangle around the long side as the axis?
一个长方形长4cm，宽2cm，以长边为轴把长方形旋转一周后，得到的立体图形的体积是多少．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3.14 * 4 * 4</gadget>
<output>50.24</output>

<result>50.24</result>