What is an artesian well? In an artesian well, the water leaps into the air like a geyser from under the earth. Sometimes a layer of porous rock or sand is buried between two layers of solid rock which water cannot permeate. At some point...
When did dinosaurs inhabit earth? Dinosaurs first appeared about 230 million years ago. This was the Triassic period, when the continents formed a single mass called Pangae Around 145 million years ago, was the Jurassic period when Africa and Europe began to drift away from...
Why is the planet Mercury so hot? Mercury spins very slowly on its axis when it travels around the sun. This means that a point on its surface is exposed to the sun for almost six months (as on Earth) at a time. This makes...
What is blood pressure? The heart pumps our blood so that it circulates throughout the body. The blood is forced out into the arteries which expand to receive the blood. But the arterial walls resist this pressure so that the blood is squeezed out into...
Who were the Mycenaeans? After the Minoans came the Mycenaeans from mainland Greece. They were both traders and warriors and built fortified towns. The walls around the city of Mycenae were built using huge stone blocks. They were good hunters too and used to hunt...
What is plasma? Fifty five percent of our blood is made up of plasma, a fluid which is clear and slightly yellowish. Many types of cells are found suspended in Plasma carries antibodies which make us immune to disease and hormones. It also transports digested...
Did the Babylonians know maths? Babylonians used cuneiform writing. Their mathematicians developed a system of counting based on the number 60. As 60 can be divided in various ways, the system proved to be very useful. It is still in use for recording time (60...
What is pitch? Loudness, pitch and tone quality distinguish one sound from another. Pitch is used to describe the high or low quality of sound. It depends on the speed of vibration of the object producing the sound. Pitch is directly proportional to the number...
Why do tidal waves occur? Tidal waves or tsunamis are caused by sudden movements of the earth under the se Such waves occur during an earthquake. Initially water is sucked away from the coast as if by a giant vaccum cleaner, followed by the tsunami...
What is the nitrogen cycle? Nitrogen is very important for the survival of plants, animals and humans. Plants take simple nitrogen compounds from the soil. Animals get nitrogen by eating plants. Nitrogen returns to the soil as waste. Bacteria convert the waste into simple nitrogen...
