運用模擬計算為什麼洗手至少要 20 秒以上，因為這樣才能把在手上的小顆粒沖走，比如說病毒... --- Particles are trapped on the rough surfaces of the hand in potential wells. In other words, they are at the bottom of a valley, and in order for them to escape, the energy from the water flow must be high enough to get them up and out of the valley.
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Particles are trapped on the rough surfaces of the hand in potential wells. In other words, they are at the bottom of a valley, and in order for them to escape, the energy from the water flow must be high enough to get them up and out of the valley.