Why are manhole covers round? Do manhole covers really need to be circular?
Manhole covers are round so that they won't fall through the hole into the sewer below them. No matter how you turn the cover, you won't be able to push the cover through the hole.
However, if you were to have square manhole covers, you would be able to rotate the cover such that one of the edges of the square cover is lined up with the diagonal line of the square hole, which would allow the cover to fall through, causing countless problems that the general public would rather avoid.
See also best riddles or new riddles.logicshort
An archeologist claims he found a Roman coin dated 46 B.C. in Egypt. How much should Louvre Museum pay for the coin? Note: Roman coins can really be found in Egypt
Nothing. That coin is as phony as a three dollar bill. In 46 B.C., they wouldn't have known how many years before Christ it was.animallogicmath
There are 100 ants on a board that is 1 meter long, each facing either left or right and walking at a pace of 1 meter per minute.
The board is so narrow that the ants cannot pass each other; when two ants walk into each other, they each instantly turn around and continue walking in the opposite direction. When an ant reaches the end of the board, it falls off the edge.
From the moment the ants start walking, what is the longest amount of time that could pass before all the ants have fallen off the plank? You can assume that each ant has infinitely small length.
The longest amount of time that could pass would be 1 minute.
If you were looking at the board from the side and could only see the silhouettes of the board and the ants, then when two ants walked into each other and turned around, it would look to you as if the ants had walked right by each other.
In fact, the effect of two ants walking into each other and then turning around is essentially the same as two ants walking past one another: we just have two ants at that point walking in opposite directions.
So we can treat the board as if the ants are walking past each other. In this case, the longest any ant can be on the board is 1 minute (since the board is 1 meter long and the ants walk at 1 meter per minute). Thus, after 1 minute, all the ants will be off the board.cleanlogicshort
How could the cowboy travel on friday, then sleep two days and then travel back home on friday.
If the horse was named Friday.logicmysteryscary
A man is found hanging in a room 30 feet off the ground. There is nothing else in the room except for a large puddle of water on the ground. The police can't see any way the man could have climbed the walls to get to where he is hanging.
How did this man hang himself?
He stood on a tall block of ice and put the noose around his neck. Once the ice melted, he was hung, and all that was left was a puddle of water on the ground.logic
A woman who lived in Germany during World War II wanted to cross the German/Swiss border in order to escape Nazi pursuers. The bridge which she is to cross is a half mile across, over a large canyon. Every three minutes a guard comes out of his bunker and checks if anyone is on the bridge. If a person is caught trying to escape German side to the Swiss side they are shot. If caught crossing the other direction without papers they are sent back. She knows that it takes at least five minutes to cross the bridge, in which time the guard will see her crossing and shoot her. How does she get across?
She waits until the guard goes inside his hunt, and begins to walk across the bridge. She gets a little more than half way, turns around, and begins to walk toward the geman side once more. The guard comes out, sees that she has no papers, and sends her "back" to the swiss side. cleanfunnylogicshort
What is represented by this BrainBat Pattern?
EST EST EST EST
How many months have 28 days?
All of them. Every month has 28 days. Some just continue on after reaching 28.logicshortwhat am I
Alone I am 24th, with a friend I am 20.
Another friend and I am unclean.
What am I?
The letter 'X'. It is the 24th letter of the alphabet, XX in Roman numerals is 20, and XXX is a label for movies that are very inappropriate (unclean).cleanlogicshort
Can you spot what's wrong with the following sentence?
PETER WAS ANGRY AT
HIMSELF BECAUSE HE
ACCIDENTALLY LEFT THE
THE KEYS TO HIS CAR
AT HIS FRIEND'S HOUSE.
It contains the word "THE" twice in a row.logic
At a local bar, three friends, Mr. Green, Mr. Red and Mr. Blue, were having a drink. One man was wearing a red suit; one a green suit; and the other a blue suit. "Have you noticed," said the man in the blue suit, "that although our suits have colors corresponding to our names, not one of us is wearing a suit that matches our own names?" Mr. Red looked at the other two and said, "You're absolutely correct." What color suit is each man wearing?
Since none of the men are wearing the color of suit that corresponds to their names, and Mr. Red was replying to the man in the blue suit, it had to be Mr. Green to whom he replied. We then know that Mr. Green is wearing a blue suit. Therefore, Mr. Red is wearing a green suit and Mr. Blue is wearing a red suit.