How does a Car Engine work?   The four pictures on the right show you what happens in a car engine. In the first diagram the piston moves down and sucks fuel in through the inlet valve. Next the piston moves up, squeezing the petrol and air mixture into the top of the cylinder. Then a spark from the sparking plug makes the fuel explode. It forces the piston down, driving...

Can a Computer Think? Before a computer can do anything at all it must be given an exact, step-by-step set of instructions called a program. It will then do just what the instructions say — no more and no less. It cannot do anything on its own. It cannot think. Computers are used nowadays in an amazing number of different ways, both to do calculations and to store information. Scientists use...

Working of The Modern Electronic Computer Modern computers can work at great speed to make calculations and control complicated operations in offices, factories and hospitals, on ships and spacecraft, at school and in the home. The pocket calculator is a kind of small computer that can do instant calculations with numbers. When you press the keys of the calculator, the numbers are changed into on-off electric signals. Each number has a...

Invention of the Computer The basic thing a computer does is calculate —like addling-up and taking away. Over two thousand ago the Greeks had a very simple machine to help them do their sums. It was called an abacus and used beads sliding wires to stand for units, tens and so on. This was not really a computer because it was worked by hand. Roth traders and early scientists had to...

How are tree frogs, flying frogs, hairy frogs and bull frogs different from the common frog? All these frogs spawn in the water in the same way as the common frog, but they each have developed peculiarities as a result of their having to find other places to live when their traditional homes have been either threatened or destroyed, for any reason. The tree frog is one of a large family...

How does a Tadpole become a Frog? If you read the answer to the previous question about what an amphibian is, you will be able to see that the story of the way the modern frog evolved, or came to be, has a lot to do with the reason for the frog spending an early part of his life as a tadpole ! For a tadpole is like a fish in...

What is an Amphibian? Amphibians are animals having a backbone that lay eggs and live in the water and also live on land. The frog is one. They evolved from lungfish which 300 million years ago learnt how to stay alive for short periods without water, because their habitat, at times, dried out. Therefore, as t hey could not breathe with their gills when out of water, in order to survive...

Did any of the dinosaurs fly? Although none of the dinosaurs could fly, living at the same time were a group of animals called pterosaurs (`winged lizards’). One of the best known pterosaurs is Pterodac-tylus, the Pterodactyl. Although Pterodac-tvlus was quite small, another flying reptile called Pteranodon, had a wingspan of 8 m (26 ft). It is unlikely that these creatures flew by flapping their wings as birds do, because they...