Virtual reality is a term used for the reconstruction of continuously changing scenes, as one would see them in real life, on a computer screen. It is basically an advanced version of computer graphics designed on the basis of real life or imaginary situations. The hardware and software required to simulate real time and real events on the computer are being developed. Logitech, the US hardware manufacturer has recently designed special computer mouse which will enable users to feed in three-dimensional (3D) spatial information into a computer. However, one would require special glasses to get a sense of screen depth and perceive the 3D effect. Computer modelling of 3D graphics has similarly become feasible.
Flight simulators that allow pilot trainees to learn flying without ever leaving the ground also create a virtually real environment of the cockpit of an actual aeroplane. This cockpit is mounted on hydraulic pumps that give the tilting effect to match the simulated movements of an aircraft. All cockpit instruments are computer-controlled showing parameters such as altitude and speed of the aircraft, weather conditions and local topography. Thus all conditions of an actual flight are duplicated so that a trainee can gain experience without taking the risk of flying a real aeroplane.
The word plastics come from the Greek word Plastikos which means ‘to shape’ or ‘able to be moulded’. All plastics are man-made polymers containing repeat units of the same group called monomer. The process by which plastics are made is called polymerization. The starting materials from which plastics are made are obtained from natural gas and crude oil.
Plastic money refers to the use of instruments like credit cards instead of cash in business transactions. It is called plastic money because credit cards are made of plastic. At present currency notes, cheques made of paper or coins are used to make payments after a purchase. Credit cards can also be used to withdraw cash from automatic teller machines. Some credit cards are used exclusively for paying call charges in public telephone booths. Plastic money also carries information about its holder in coded form which makes it theft-proof. No one, but the holder is able to use the card.
A satellite that appears to be stationary in the sky is said to be in ‘geostationary’ orbit. It is launched in such a manner that it orbits the earth directly over its equator at a height of 36,000 kms. At that height, its orbital speed is such that it completes one orbit in 24 hours. Since the earth also completes one rotation around its axis in 24 hours, the satellite appears stationary in the sky from earth.
It is a family of newly discovered, the third allotropic form of carbon, quite distinct in structure and properties from the two earlier known forms — graphite and diamond. The first member of this new form of carbon, also called fullerene, was discovered in 1985 by a team of scientists led by Harold Kroto of the University of Sussex, U.K. and Richard Smalley of the Rice University, USA. Unlike graphite which has a plane layer of six-membered carbon rings and diamond which has a three-dimensional network of tetrahedrally bonded carbons, the newly discovered molecules have spherical cage-like structure, such as the famous geodesic dome invented by Buckminster Fuller. That is why the name fullerene. The most stable of these has 60 carbon atoms. The C-60 molecule has a magenta colour.