Did You Know? How Does the Dreidel Not Fall?

How Does the Dreidel Not Fall?

What makes the dreidel spin on its point and not fall? Well, it's the spinning itself that allows it to stand without falling. This spinning force is called "angular momentum," which means rotational motion around an axis located in the center. When the dreidel starts to fall, one side becomes lower and is pulled more by gravity. But because of the rotational motion, very quickly that low part becomes high again, and another part of the dreidel becomes low. The gravity continues to act on the dreidel, but at every moment, it acts on a different point of the dreidel, keeping it upright for some time.

Who Invented the Submarine?

As far back as 1578, an English inventor named William Bourne designed a prototype for a submarine. In the same century, Leonardo da Vinci also sketched plans for a submarine. However, the first actual submarine was built in England in 1620, following the developments of the Dutch inventor Cornelis Drebbel, which were based on William Bourne's designs. The submarines developed by Drebbel were tested in the River Thames and could dive to a depth of only four meters.

Who Is the Strongest Mammal?

Among sea creatures, there are certainly stronger animals. But among mammals, the elephant is the strongest. An adult elephant can carry a weight of about 9 tons on its back - that's equivalent to about 130 people (or approximately 250 children).

The elephant also makes one of the loudest sounds known in the animal kingdom: the trumpet sound it produces with its trunk reaches a strength of about 110 decibels, and therefore it serves as a communication tool for elephants over long distances.