Do you know the first cosmic velocity? To make the spaceship move around the earth, the minimum speed when launching the spaceship is 7.9 km/s, this speed is called the first cosmic speed. If a person walks at a speed of about 4 km/h, how do you feel about it?
你知道第一宇宙速度吗？要想使航天飞船绕着地球运动，发射飞船时的最小速度是7.9千米/秒，这个速度叫作第一宇宙速度．如果人步行的速度大约为4千米/时，比一比、说一说，你有什么感受？
<gadget id="calculator">3_600 / 4</gadget>
<output>900</output>

<gadget id="calculator">7.9 * 900</gadget>
<output>7_110</output>

<result>7_110</result>