How do steel ships float?

When the British engineer Ismargad Kingdom Brunnel tried to convince the shipping companies to produce a ship made of steel, the idea was received with much ridicule. “Everybody knows that steel sinks in water!” said the shipyard owners. “How could you suggest that a ship made of steel could float on water?”

But despite the ridicule, today most ships are made of metal. The principle which enables a metal ship to float is very simple. Think of it this way: the ship that “sits” in the water creates a depression, meaning, the water moves to make room for the ship. If the ship weighs less than the water needed to fill this depression, it will float. Because of the shape of the ship and the fact that it is hollow, it pushes aside a large quantity of water that weighs more than itself, and therefore it is able to float.

How does a parachute work?

When a man jumps out of a plane, his drop velocity can reach 100 mph! If he touches the ground at that speed, he will hit it extremely hard and be killed.

The purpose of the parachute is to reduce the rate of his descent so he can survive the impact when he touches the ground.

During the parachutist’s jump, the folded parachute is strapped to his back by a special belt. When he releases the parachute, it opens and unfolds. As the wind presses against the parachute’s inner surface, the air pressure resists the gravity that pulls the man downward. This reduces the rate of the parachutist’s drop and ensures a safe landing.

What are hieroglyphics?

Hieroglyphics is a writing system used in ancient Egypt that uses symbols and drawings to convey different messages. Hieroglyphics is very complex to learn because it uses over 2,000 symbols, composing words and expressions. Each symbol represents an object, and every object represents the opening sound of the name of the object or an idea related to the object. It is no wonder, then, that very few Egyptians knew how to read and write, and literacy was unique to the “Khartoumim,” the ancient priests of Egypt.

Today, the Hebrew word used to describe an illegible, unreadable script is “Khartoumim writing” because for many centuries the archeologists could not understand the writings left behind by the Khartoumim.

How do crickets make sounds?

Many of us are familiar with the monotonic chirp of house crickets, but not with their special way of making this sad sound. The cricket does not chirp with its mouth; its music-organ actually is its upper wings. One of these wings is ridged while the other is hard and smooth. When the cricket wants to chirp, it rubs one wing against the other. The sound that the two wings make is amplified by the wing’s membrane, which the cricket uses as a speaker.

4 Photos – you can choose your own – but if you need help – I found these.

  1. Ship – # 16843331 OR 17629652
  2. Parachute – # 4949350
  3. Hieroglyphics – # 8248557 OR 28174709 – need to crop out the sphinx.
  4. Cricket – # 13762721 –need to delete the hearts.

1 Blurb


This month’s question was sent by Michael of Brooklyn NY.

Dear Professor,

Do all bees live in hives?

Dear Michael,

The honeybees we are familiar with live, as we know, in hives, and that is where they lead their lives in strict order. However, unlike the hive bees, there are wild bees that live alone. These bees build nests for their eggs in holes in the ground, plant stalks, and trees. In Israel there are over 600 families of wild bees that live on their own!