Why do we need to light a fire at the bottom of the pot when boiling water? Why not burn the surface? This is actually a very interesting piece of physics knowledge. If you use fire to burn the surface of water, some of the water in the upper layer will indeed heat up quickly, but the density of hot water is less than that of cold water, so they will continue to stay in the upper layer. The cold water in the lower layer cannot reach the upper layer to obtain heat, and can only obtain a little bit of heat seeping down from the upper layer. When the hot water in the upper layer gets a lot of heat, it turns into water vapor and escapes out of the pot, but the water below is still cold. Facing the capital at the top, where should the bottom go?
Concept: The sadness and helplessness of beating workers