White sands

Walk along a beach at low tide when the sand is firm and wet. At each step, the sand immediately around your foot dries out and turns white. Why? The popular answer, that your weight ‘squeezes the water out,” is incorrect: sand doesn’t behave like a sponge. So what does cause the whitening?

_
Click here for the solution

Before you step on it. the sand is packed as tightly as it can be under natural conditions. Your weight disturbs the sand, making the grains less efficiently packed. The sand is forced to occupy more volume and rises above the water level. becoming dry and white. The water rises more slowly. by capillary action, so it takes a few seconds or more before the sand gets wet and dark again.

more riddles

How does the man escape?

A man is trapped in a room. The room has only two possible exits: two doors. Through the first door there is a room constructed from magnifying glass. The blazing hot sun instantly fries anything or anyone that enters. Through the second door there is a fire-breathing...

read more

Five-digit number

What is the five-digit number, no zeroes, in which the second digit is three times the first, the third is one more than the second, the fourth is four times the first, and the last is one-half more than the second? The number is: 26789 more...

read more

The peanuts and the monkey

Five men checked into a hotel with a bag of peanuts and a monkey. They planned on dividing the peanuts evenly the following morning. However, during the night, one of the men got up, divided the peanuts into five equal parts, took his fifth and had one leftover peanut...

read more

How many children does Mr. Smith have?

Mr. Smith has 4 daughters. Each of his daughters has a brother. How many children does Mr. Smith have? He has 5 children, all of the daughters have the same 1 brother. more riddlesDonec rutrum congue leo eget malesuada....

read more