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二、热空气比冷空气轻我们知道空气在受热时体积将会膨胀,也就是说同体积的热空气的密度要比冷空气的密度小,因此,它的重量也就比冷空气轻.本教具所演示的就是同体积的热空气和冷空气重量的比较,可以清楚地看到热空气比冷空气轻.1.材料:易拉罐、车辐条、圆珠笔尖、大头针、铅丝、木块等.2.制法:用薄铁皮按图所示 要求剪一指针,沿线折叠后,使其夹在车辐条的中部,并在A处钻一恰好能将圆珠笔尖插入的小孔,笔尖垂直插入后,为使其牢固可滴少许502胶液或焊接.
Second, the hot air is lighter than the cold air. We know that when the air is heated, the volume will expand, which means that the same volume of hot air has a lower density than the cold air. Therefore, its weight is lighter than that of cold air. The teaching aid demonstrated is the comparison of the same volume of hot air and cold air weight. It can be clearly seen that the hot air is lighter than the cold air. 1.Materials: cans, spokes, ballpoint pen tips, pins, lead wire, wooden blocks, etc. Method of manufacture: Use a thin sheet of iron to cut a pointer as shown in the figure. After folding along the line, sandwich it in the middle of the spokes of the car, drill a hole in the A just enough to insert the ballpoint pen tip, and insert the pen tip vertically. To make it strong enough to drop a little 502 glue or welding.