今天我给大家介绍一下动力臂和阻力臂。举一个例子：跷跷板。
Today I'd like to introduce the power arm and drag arm. For example: seesaw.
在左边的是动力臂，右边的是阻力臂，中间的是支点。下面详细介绍一下:假如把物体放在阻力臂上，翘翘板的阻力臂就会迅速下降，而动力臂就会迅速翘起，而且压起动力臂就会很费劲。不过，动力臂越长，用的劲就越少；动力臂越短，用的劲就越多。
On the left is the power arm, on the right is the resistance arm, and in the middle is the fulcrum. Here is a detailed introduction: if the object is placed on the resistance arm, the resistance arm of the warping plate will fall rapidly, and the power arm will rise rapidly, and it will be very difficult to press up the power arm. However, the longer the power arm, the less force is used; the shorter the power arm, the more force is used.
比如，生活中砸钉子就是这个原理，锤子头是阻力臂，杆是动力臂，手越往后用的劲就越小。小朋友们想一想，生活中还有什么现象用到动力臂和阻力臂
For example, this is the principle of smashing nails in life. The hammer head is the resistance arm, and the rod is the power arm. The more backward the hand is, the less force it will use. Let's think about what else we can do in our life: power arm and resistance arm
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