Optical illusions![kelvin (6-10 17:32, Long long ago)] [ 传统版 | sForum ][登录后回复]1楼

Rotating flowers...[kelvin (6-10 17:38, Long long ago)] [ 传统版 | sForum ][登录后回复]2楼

(引用 kelvin:Rotating flowers... ...)Straight lines or curve?[kelvin (6-10 17:39, Long long ago)] [ 传统版 | sForum ][登录后回复]3楼

(引用 kelvin:Straight lines or curve? ...)waves or still...[kelvin (6-10 17:40, Long long ago)] [ 传统版 | sForum ][登录后回复]4楼

(引用 kelvin:waves or still... ...)Concentric gray circles appear to be spirals.[kelvin (6-10 17:40, Long long ago)] [ 传统版 | sForum ][登录后回复]5楼

(引用 kelvin:Concentric gray circles appear to be spirals. ...)Color swamp...moving or not?[kelvin (6-10 17:43, Long long ago)] [ 传统版 | sForum ][登录后回复]6楼

(引用 kelvin:Color swamp...moving or not? ...)How many faces? Where is the tenth?[kelvin (6-10 17:45, Long long ago)] [ 传统版 | sForum ][登录后回复]7楼

(引用 kelvin:How many faces? Where is the tenth? ...)Now count aloud the ' F' s in that sentence.FINISHED FILES ARE THE RE- SULT OF YEARS OF SCIENTIF- IC STUDY COMBINED WITH THE EXPERIENCE OF YEARS.

[kelvin (6-10 17:46, Long long ago)] [ 传统版 | sForum ][登录后回复]8楼

(引用 kelvin:Now count aloud the ' F' s in that sentence.FINISHED FILES ARE THE RE- SULT OF YEARS OF SCIENTIF- IC STUDY COMBINED WITH THE EXP...)ANSWER:
There are six F's in the sentence. One of average intelligence finds
three of them. If you spotted four, you're above average. If you
got five, you can turn your nose at most anybody. If you caught six,
you are a genius. There is no catch. Many people forget the OFs. The
human brain tends to see them as "V's" instead of "F's".
[kelvin (6-10 17:46, Long long ago)] [ 传统版 | sForum ][登录后回复]9楼

Brain teasers...1) A big fat Indian and a small thin Indian were sitting outside a teepee, each smoking a pipe. The little Indian was the son of the big Indian, but the big Indian was not the little Indian's father. How come?

[kelvin (6-10 17:47, Long long ago)] [ 传统版 | sForum ][登录后回复]10楼

(引用 kelvin:Brain teasers...1) A big fat Indian and a small thin Indian were sitting outside a teepee, each smoking a pipe. The little In...)2) Mary's husband's father-in-law is Mary's husband's brother's brother-in-law, and Mary's sister-in-law is Mary's brother's stepmother. How did this happen?
[kelvin (6-10 17:47, Long long ago)] [ 传统版 | sForum ][登录后回复]11楼

(引用 kelvin:2) Mary's husband's father-in-law is Mary's husband's brother's brother-in-law, and Mary's sister-in-law is Mary's brother's ...)Over the side of a boat floating in a harbor3) Over the side of a boat floating in a harbor there hangs a rope ladder containing ten rungs. Each rung is one foot from the next one and the bottom rung is resting on the surface of the water. The tide rises at a rate of one foot an hour. How long will it take the water to reach the top rung?
[kelvin (6-10 17:47, Long long ago)] [ 传统版 | sForum ][登录后回复]12楼

(引用 kelvin:Over the side of a boat floating in a harbor3) Over the side of a boat floating in a harbor there hangs a rope ladder contain...)Timothy and Urban play a game with two dice.Timothy and Urban play a game with two dice. But they do not use the numbers. Some of the faces are painted red and the others blue.
Each player throws the dice in turn. Timothy wins when the two top faces are the same color. Urban wins when the colors are different. Their chances are even.
The first die has 5 red faces and 1 blue face. How many red and how many blue are there on the second die?
[kelvin (6-10 17:48, Long long ago)] [ 传统版 | sForum ][登录后回复]13楼

(引用 kelvin:Brain teasers...1) A big fat Indian and a small thin Indian were sitting outside a teepee, each smoking a pipe. The little In...)Ferrari & Maserati...A Ferrari is traveling at 30 miles per hour on a head-on collision course with a Maserati, which is being driven at a leisurely 20 miles per hour. When the two cars are exactly 50 miles apart, a very fast fly leaves the front fender of the Ferrari and travels towards the Maserati at 100 miles per hour. When it reaches the Maserati, it instantly reverses direction and flies back to the Ferrari and continues winging back and forth between the rapidly approaching cars. At the moment the two cars collide, what is the total distance the fly has covered?

[kelvin (6-10 17:48, Long long ago)] [ 传统版 | sForum ][登录后回复]14楼

(引用 kelvin:Ferrari & Maserati...A Ferrari is traveling at 30 miles per hour on a head-on collision course with a Maserati, which is being d...){Solution}

At first glance it may seem that a horrendous calculation is necessary to solve this: the sum of an infinite series of numbers that get smaller and smaller as the cars approach each other. But if you focus on time rather than distance, a solution is easy. The cars are 50 miles apart and traveling towards each other at a combined speed of 50 miles per hour, so they will meet in one hour. In that hour, a fly that flies at 100 miles per hour will naturally travel 100 miles.

[kelvin (6-10 17:49, Long long ago)] [ 传统版 | sForum ][登录后回复]15楼

(引用 kelvin:Brain teasers...1) A big fat Indian and a small thin Indian were sitting outside a teepee, each smoking a pipe. The little In...)Short questions...1) If it takes twenty minutes to hard-boil one goose egg, how long will it take to hard-boil four goose eggs? e

2) Is there a 4th of July in England? Yes or No?

3) Some months have 31 days. How many have 28?

4) Can a man in California marry his widow's sister?

5) Take the number 30, divide it by 1/2, and then add 10.
What do you get?

6) A doctor gives you three pills and tells you to take one every half
an hour. How long will the pills last?

7) A farmer has 17 sheep. All but 9 of them die. How many sheep are
left?

8) How many animals of each species did Moses have on the ark?

9) A butcher in the market is 5' 10 tall. What does he weigh?


[kelvin (6-10 17:50, Long long ago)] [ 传统版 | sForum ][登录后回复]16楼

You Cannot See Everything! - Blindspot... Close your right eye, or cover it with your hand Stare at the black circle (below) While looking at the circle, use 'side' (peripheral) vision to see the cross Slowly move your head towards the screen The cross should completely disappear Move closer, and it will re-appear! [kelvin (6-10 17:54, Long long ago)] [ 传统版 | sForum ][登录后回复]17楼

Which is longer?[kelvin (6-10 17:57, Long long ago)] [ 传统版 | sForum ][登录后回复]18楼

(引用 kelvin:Which is longer? ...)How many colors?[kelvin (6-10 17:58, Long long ago)] [ 传统版 | sForum ][登录后回复]19楼

(引用 kelvin:How many colors? ...)Which circle is larger?http://www.harmsy.freeuk.com/oimages/flowers.gif[kelvin (6-10 17:59, Long long ago)] [ 传统版 | sForum ][登录后回复]20楼