Science & Mathematics Questions & Answers

This is due to the pull of the earth’s gravity. If there were no gravity the stone would remain in the air. When the stone is thrown into the air, a force is applied to it which is greater than the pull of gravity. But as it rises higher the force becomes weaker until the stone reaches a point where …

Stainless steel resists rust because it contains a high proportion of chromium to carbon. Before the arrival of this alloy just before the First World War, knives and other household articles made of steel easily rusted unless very carefully dried. It was an English researcher named Harry Brearley who discovered that rust was encouraged by the carbon in steel and …

The pencil appears to bend owing to the refraction of light, or the change in direction of light when it passes through transparent materials. The light rays coming from the submerged part of the pencil are bent as they live the water. Light rays are reflected and absorbed by opaque materials such as glass, air, water, oil and certain plastics, …

It is the built-in skew or twist in a boomerang combined with its spinning motion that makes it return to the thrower. At first people believed that air, pressing on the lower flat surface and passing over the upper rounded face, was responsible for the return flight. But T.L. Mitchell, a Scottish explorer of Australia, gave the true explanation early …

Some animals and birds make use of tools. There are some good examples among the birds. For example, the song thrush commonly feeds on snails which it opens by flying up with the shell in its bill and dropping the snail on convenient stone. The bird often uses the same stone on a number of occasions so that it may …

The main reason we are able to float is that the density of our bodies is relatively less than the density of water. A large part of the human body is made up of air and water. Buoyancy-the ability to float depends on the individual. But with experience it is possible to improve your body balance, in other words to …

The lowest layer of the atmosphere is called the troposphere. Above it is the second layer, the stratosphere. Around the border between the two layers are strong winds, called jet streams, which blow mostly from west to east at over 160 km/h (100mph). Pilots avoid flying into them, but they often use them as tail winds, so as to increase …

Zero net is the modern strategy to regulate pollution by controlling the use of energy in constructions. The term ‘zero net energy’ is used when the amount of energy utilised by a building is equal to the amount provided by on-site or nearby renewable energy resources. Such buildings are also called zero energy buildings and are gaining popularity in US …

The word is derived from the Greek word xeros, meaning dry. It refers to landscaping which doesn’t require additional water. It uses plants which are suited to the local climate, and practitioners ensure that water doesn’t evaporate or run off. Xeriscaping is also called zeroscaping, drought-tolerant landscaping, smartscaping and waterconserving landscapes. It was developed by the water department of Denver, …

It is the use of non-human animal cells, tissues and organs in human patients. These cells can be implanted or enclosed in a device used outside the body. The tissue is harvested from animals already being butchered. Immune rejection remains the biggest challenge for this. A worrisome element of xenotransplant is the potential for infectious disease from donor animals which …