Everyday physics
Why ordinary things do what they do. 3 reviewed articles here, each naming the sources behind it.
What everyday physics covers here
Why ordinary things do what they do. These are the questions a general reference work tends not to answer well — comparisons, causes, and the distinctions people routinely conflate.
Every one of these was read by a person
An article appears in this list only once somebody has checked it against its sources. Drafts and short articles are readable but are kept out of search and out of this list.
- Why does ice float? — Ice floats because water is one of the very few substances that expands when it freezes — about 9% — so a give…
- Does hot water freeze faster than cold? — Sometimes, under some conditions, in some setups — and after decades of experiments there is still no agreed e…
- Why is the sky blue but sunsets red? — Both come from the same effect: air molecules scatter short wavelengths far more strongly than long ones, so o…
Questions
Why does ice float?
Ice floats because water is one of the very few substances that expands when it freezes — about 9% — so a given mass of ice takes up more space than the same mass of liquid water and is therefore less dense.
Does hot water freeze faster than cold?
Sometimes, under some conditions, in some setups — and after decades of experiments there is still no agreed explanation, which makes this a better example of how a scientific question stays open than of a settled fact.
Why is the sky blue but sunsets red?
Both come from the same effect: air molecules scatter short wavelengths far more strongly than long ones, so overhead you see scattered blue light, and at sunset — when the light has travelled through far more atmosphere — the blue has been scattered away before it reaches you and what is left is red.