图片中的展品名叫自己拉自己,听到这个名字,很多同学一定会很奇怪,这怎么可能呢?不过,科技馆里的这件展品确实可以帮助我们实现。当你坐在椅子上,用双手交替向下拉面前的绳索,你就会发现你可以把自己拉起来。其实,这件展品的奥秘就是利用了滑轮组。仔细观察,可以发现这件展品是由椅子、滑轮和绳索组成的。滑轮是杠杆的变形,属于杠杆类简单机械。中心轴固定不动的滑轮叫定滑轮,定滑轮实质上是一个等臂的杠杆,它不省力也不费力,但它却可以改变作用力的方向。中心轴跟重物一起移动的滑轮叫动滑轮,而动滑轮实质上是一个动力臂为阻力臂二倍的杠杆,它可以省去二分之一的力 The exhibits in the picture call themselves to pull their own name, many students will be very strange to hear this how possible? However, this museum exhibits can really help us to achieve. As you sit in your chair and use your hands to pull down the ropes alternately in front of you, you will find that you can pull yourself up. In fact, the mystery of this exhibit is the use of pulley blocks. After careful observation, you can see that the exhibit is made up of chairs, pulleys and ropes. Pulley is the deformation of the lever, belonging to the lever type simple machinery. The central axis of the fixed pulley called fixed pulley, fixed pulley is essentially an arm lever, it is not effortless and effortless, but it can change the direction of the force. The central axis moves with the weight of the pulley called pulley, while the movable pulley is essentially a power arm for the resistance of the arm twice, it can save half of the force