#water
Questions about “water”.
25 articles
Why does road salt melt ice?
On snowy mornings, roads and bridges are often scattered with white grains. Why does salt make ice melt? And why does it work worse the colder it gets?
Do your tears change with your feelings?
Tears of sadness and tears from chopping onions look like the same drops. But are they the same inside? A story of research on tears spanning more than 40 years.
Where did Earth’s water come from?
Oceans cover 70 percent of Earth’s surface. Where all that water came from, though, is one of the great open questions in science.
How does a steel ship float?
Drop an iron nail into water and it sinks at once, yet ships built from tens of thousands of tons of steel float. The difference comes down not to the metal, but to its shape.
Why do geysers erupt?
A quiet hole in the ground suddenly sends boiling water high into the sky, almost like clockwork. Behind the spectacle lies an underground “pressure cooker.”
Why do pine cones open and close?
A pine cone brought home seems to clench shut on rainy days and spread open again on sunny ones. What’s more, it does this even though the cone is “dead.”
Why does popcorn pop?
Little kernels leaping out of the pan with a pop. Ordinary corn won’t do this. Inside each kernel lies something like a pressure cooker, and an unexpected “leg.”
Did Archimedes really shout “Eureka”?
A genius makes a great discovery in the bath and runs into the street naked. The most famous story in the history of science comes with more than a few question marks.
How does moss come back to life after drying out?
Pour water on moss that has dried brown and brittle, and the green comes rushing back. What was going on inside while it looked dead?
Why does ice float on water?
Most substances sink in their own liquid once they solidify. Yet the ice in your glass bobs happily at the top. What makes water so different?
How much does a cloud weigh?
Clouds look as light as cotton candy. If you could set one on a scale, how far would the needle swing? And why don’t clouds fall out of the sky?
Is a baobab’s trunk full of water?
A massive, stubby trunk topped with branches that look like roots. What exactly is packed inside the bulk of a baobab standing on the savanna?
Why is ice slippery?
Almost everyone has lost their footing on an icy path. Yet the reason behind something so familiar is a puzzle physicists have argued over for more than 170 years.
What is the tallest waterfall in the world?
Somewhere, water plunges from a height far greater than Tokyo Skytree. And beneath the sea, an even bigger “invisible waterfall” is flowing.
Why is milk white?
Milk poured into a glass is a dazzling white. Yet search the milk from top to bottom, and you won’t find a single “white pigment” responsible for it.
Why does water boil at a lower temperature on a mountain?
Water boils at 100°C—or so we learned in school. That rule doesn’t hold everywhere. High on a mountain, a pot of water behaves very differently.
How did people keep things cold before refrigerators?
Life without a refrigerator in the kitchen is hard to imagine today. Before electricity, people went to astonishing lengths to get their hands on a little cold.
Why do you float in the Dead Sea?
Lie back on the water and open a newspaper. A lake famous for photos like that lets even non-swimmers stay afloat. How does it work?
Can water stay liquid below 0°C?
Tap a bottle of water fresh from the freezer, and it turns to slush before your eyes. Behind this magic trick lies a surprising property of water.
What happens if you cry in space?
When we’re sad or happy, tears roll down our cheeks. But if you cry aboard a spacecraft, where there is no up or down, where do the tears go?
What percentage of the human body is water?
People often say the human body is mostly water. But how much, exactly? It turns out the share varies surprisingly with age and sex.
Did vending machines exist in ancient times?
Drop in some coins, press a button, and out comes a cold drink. Trace the idea behind the vending machine back far enough and you end up nearly 2,000 years ago.
Did people in Edo-period Japan bathe every day?
In Japanese period dramas, the cramped tenement houses have kitchens but no bathrooms. Even so, the people of old Tokyo seem to have been remarkably fond of keeping clean.
Is it true that pure water doesn’t conduct electricity?
We’re taught never to touch an outlet with wet hands, yet we also hear that pure water doesn’t conduct electricity. So which is it?
Can you swim any stroke in a freestyle race?
Say “freestyle” and everyone pictures the front crawl. So what would happen if you entered a freestyle race and swam breaststroke or backstroke? Would you be disqualified?