A full glass of water with a single ice cube sits on a table. When the ice has completely melted, will the level of the water have increased, decreased or remain unchanged?
The water level remains unchanged because the ice cube displaces its own weight. If you’re not convinced, read Archimedes’ Principle, which states that any floating object displaces its own weight of fluid. Still not convinced? Here are a few moresources.
A variation of this brain teaser includes laser printers (they were invented by Gary Starkweather) and bulletproof vests (invented by Casimir Zeglen using silk, though modern vests use Kevlar, so it’s halfway right).
A key. It has a jagged cut in order to fit the lock. A locked door keeps people out and the keyhole is dark. Key rings are a common way to hold a set of keys, and when you’re using a key that one is quiet, but the rest jingle and jangle.
The first four letters are a variation of the weather. The third through seventh letters give support but also could used when someone is executed. And the last three letters forms the name of a person.
The letters “kst” are in the word, “in” is at the beginning, with “and” at the end. I know, it’s awkwardly worded but otherwise it wouldn’t be a riddle.
Ten seconds is 1/6 of a minute and 1 minute is 1/60 of an hour, so 10 seconds is 1/360 of an hour.
If you graph her trip with the speed on the y-axis and the time on the x-axis, you get a triangle with height of 60 mph and width of 1/360 of an hour. To calculate the area of the triangle, you multiply 1/2 × 1/360 × 60 = 1/12.
Three philosophers are taking a nap under a tree. While they’re asleep, a small boy smears their noses with red berries. When they awake, they each begin to laugh, thinking the other two are laughing at each other.
But then one philosopher stops laughing, realizing his nose is red too. How did he come to this conclusion?
Let’s call the philosopher’s A, B and C. A reasoned that B was confident his nose wasn’t red. If B saw A’s nose wasn’t red, he would be surprised that C was laughing, because C would have nothing to laugh at. But B wasn’t surprised, therefore, A correctly reasoned his nose was smeared.