What is latent heat? Materials cannot absorb heat indefinitely. After a while the heat makes the substance change its state. If the substance becomes cool and turns back into a solid or liquid state, the latent heat is released into the surroundings.
What is a miracle? A miracle is something that cannot be explained using reason and logic. It is a supernatural event. Sometimes things that happen are beyond our understanding and those of us who are religious put it down to divine intervention. Such events are...
How is copper obtained from ore? Copper is found in nature in two forms—native copper or the metal itself or in mineral ore, where it is combined with other elements. Copper ore is refined to get copper. The ore is crushed and washed in flotation...
Do molecules have weight? A molecule’s weight depends on the weight of the atoms it is made of. The weight of the atom depends on the number of protons and neutrons in the nucleus of an atom. For example, hydrogen is a simple atom which...
Why does ice float? The Archimedes principle says that any object when placed in liquid is buoyed up or held up by a force equal to the weight of the displaced liquid. Ice is nine-tenths as heavy as water. So about nine-tenths of an iceberg...
What is slate? Millions of years ago, fine grains of clay particles settled on the bottom of lakes and seas, forming soft mud. This became hardened mud-rock called shale. Around this time, the earth’s crust moved and shifted. The shale layers, covered by beds of...
What is virgin wool? Wool is sometimes used more than once as it is valuable. Old wool is recovered, cleaned and used again. To protect the interests of buyers, some governments made laws which laid down that woollen products should have a label showing the...
Why do we have leap years? There are 365 and one quarter days to each year. We add an extra day into the calendar every four years to make a leap year. This ensures that the year does not slowly become out of step with...
What is the eye of a hurricane? The low pressure region in the centre of a hurricane is called the eye of the hurricane. Hurricanes are spiralling winds going round and round very fast. When the wind speed is about 120 km an hour the...
What is a UFO? A UFO stands for Unidentified Flying Object. It is a flying object of which nothing is known i.e., what it is or where it has come from. They are also called flying saucers colloquially. Some people think that they are the...
