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Your five-year-old knows it: When it comes to building sand castles at the beach, wet sand is much better than dry. If you fill your bucket with dry sand and turn it over, you’re likely to end up with a tumbled ruin, not a proud tower or turret1. Any junior civil engineer will tell you to use damp sand from the water’s edge to construct proper parapets. We'll learn why wet sand sticks on today's Moment Of Science. Fortunately for beach-goers everywhere, a group of physicists2 at Notre Dame3 tackled this sticky problem. They discovered that wet sand sticks together for exactly the same reason water beads4 up on wax paper: a phenomenon called surface tension.
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1 turret | |
n.塔楼,角塔 | |
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2 physicists | |
物理学家( physicist的名词复数 ) | |
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3 dame | |
n.女士 | |
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4 beads | |
n.(空心)小珠子( bead的名词复数 );水珠;珠子项链 | |
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