Why does wet sand stick together to form sand castles and dry sand falls apart?
We think of ice as snowflakes, ice cubes, snow cones, and dangerous patches on the sidewalk. Scientists have many different ways of categorizing ice too!
It’s summertime, and you’re on vacation. You sit beside a quiet pond, fishing, trying to relax, trying to think about nothing at all. You watch the leaves stirring, the water rippling in the sunshine, and the water bugs standing on the surface of the water. Wait, how are those bugs standing on the surface!? Learn more on this Moment of Science.
Water bugs manage to stand on the surface of a pond, because the pads of their feet resist contact with the water just like wax paper does. This allows the bug to rest on the thin film of surface tension that naturally covers the pond. This surface tension film is caused by the strong attraction the surface water molecules have toward each other, as well as toward the water beneath them. Learn more on this Moment of Science.
Your five-year-old knows 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 turret. Any junior civil engineer will tell you to use damp sand from the water’s edge to construct proper parapets. Learn more on this Moment of Science.
Ever wonder how superglue works? Find out on this Moment of Science.
Air molecules are naturally elastic–they don’t stick together like water molecules, but rather bounce off each other in the open.
Microwaves are low energy electromagnetic waves that have so little energy they can’t trigger chemical reactions in the molecules they encounter.