Here’s an amazing way to get a hard-boiled egg into a bottle, even though the mouth of the boiled is smaller than the egg! What’s more, you don’t even need to touch the egg to get it to go in! For this experiment you will need: ·a hard-boiled egg ·a glass bottle with a mouth just slightly smaller than the egg (a fruit-drink bottle works well) ·a 8-cm by 8-cm(3-inch by 3-inch)piece of newspaper ·a match Remove the shell from the egg. Set the egg on the mouth of the bottle to see that the egg does not fit through the mouth. Light the paper. Remove the egg from the mouth of the bottle and drop the burning paper into the bottle. Before the fire goes out, set the egg back onto the mouth of the bottle. Within a few seconds the egg will squeeze(挤) through the mouth and into the bottle. As it entered the bottle, the egg may have broken into pieces. This happens when the diameter(直径) of the egg is more than about 0.5 cm(about 3/16 inch) larger than the diameter of the bottle’s opening. Why does the egg slide into the bottle, even though no one is pushing it? Because the pressure of the air is pushing it. Before the burning paper is put into the bottle, the pressure of the air inside is the same as outside. The burning paper, however, heats the air inside. This causes the air inside to expand. When the egg is placed on top of the bottle, it seals(封住) the bottle. When the fire goes out, the air inside cools. As it cools, the air contracts(紧缩), and the pressure of the air inside becomes less than the pressure outside. Then, the higher outside pressure pushes the egg into the bottle! 小题1:The best title of this passage can be .
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