Why do astronauts float in space? Once they are outside the earth’s gravitational field, astronauts are weightless. Their mass is the same but there is no gravity to lend the mass weight. So, the astronauts have to be tethered to something to prevent them from...
What does a pH value measure? pH is an abbreviation that stands for ‘power of hydrogen’. The pH value tells us how concentrated the hydrogen ions in a substance are. If the pH value is below 7, the substance is acidic. If it is above...
What is a centrifugal force? Forces usually act in a linear manner or straight line unless there is something to change their direction. For example, take a roller coaster which may go upside down. There is a forward-acting force which keeps it on the tracks...
Do fish build homes? Unlike birds, fish may lay hundreds of eggs. And some fish are known to build nests to safeguard their young. The stickleback is a fish that lives in ponds and rivers in Europe. It builds its nest using plant fibres in...
Why do snakes shed their skin? We have to live with the same skin year after year but snakes are luckier. They shed their skin many times a year. The process is called sloughing. The old skin wears out as the snakes crawl on the...
What is radioactivity? Some of the elements we know are not stable. Their nuclei are always breaking down or decaying as they shed particles in order to become stable. This is called radioactivity. The particles that they emit are called radiation. There are three of...
Which Egyptian pharaoh’s tomb has survived? Many of the pharaohs’ tombs were plundered. However, in 1922, archaeologists came across the tomb of the young pharaoh, Tutankhamun. He died at the age of 18. His tomb was intact and contained many priceless treasures, including a golden...
What is Velcro? Velcro is the name given to nylon strips which stick to each other when pressed together but which can also be easily ripped apart. They are sometimes used in shoes instead of the traditional laces. It was invented by Swiss engineer George...
What is the origin of fairy tales? In the old times people believed in fairies. It is believed that fairy tales are based on strange or unusual events that people had experienced.. These events when narrated over generations gathered into an oral tradition of stories...
Who are Mormons? A Mormons belong to the church of Jesus Christ of Latter-day Saints. The church was founded by Joseph Smith in Fayette, New York, in 1830. After Brigham Young became its president the church was moved to Salt Lake Valley, Utah, in 1847,...
