Science & Mathematics Questions & Answers

The diesel engine is more efficient than the petrol engine because of its greater thermal efficiency. This means that the ratio of the work done by the engine to the amount of heat supplied is higher. Since the heat in this case comes from fuel-oil, it is not possible to convert all the heat energy in the fuel into useful …

Blunderbuss probably derives its name from the German donder buchse, ‘thunder gun’. The gun was built with a bell-shaped barrel – wider at the muzzle than the breech. This amplified the noise of the explosion. The weapon was loaded with a number of small balls and it was thought that the bell-mouth would cause the shot to spread. But it …

Technically, it is not possible to light an electric bulb without drawing input greater than zero watts. Zero watts is actually not zero, but refers to the minimum wattage. The inaccurate electric meters of the early days could not measure such a negligible amount of consumption as during those days, the watt hour meter had a rotating disc and when …

When we are tickled, we laugh and wriggle. This is what is termed a reflex action, an action which takes place without any thought on our part. Balancing ourselves when we walk is another example of reflex action. We retain our balance automatically, without thinking about it, but when we try to tickle ourselves, the brain knows that we are …

Atmospheric pressure, which is about 1 kg per sqcm of area, presses down on our body from all sides, but we don’t feel it as it is balanced by fluid pressure from inside our body. We can feel the difference during rainy season or when we go to places where atmospheric pressure is less, like hill stations, where due to …

A regular motorcycle has a ‘sequential’ manual transmission, meaning you can only shift up or down one gear at a time. It is also designed to spin one way only. Adding reverse would require the crankshaft to spin backwards, or a much larger, heavier, expensive transmission. So it is easiest to dismount and push the bike backwards.

All species of animals, including man, of course, have developed very gradually over millions and millions of years. In this way, each animal strengthens and improves those parts of its body which are particularly useful, and the various parts which are not so useful diminish or are adapted. This evolution happens very, very slowly, and changes can only be seen …

Trees do not grow on mountain tops either because the situation is too exposed, or because the soil is too thin or too frozen to allow their roots to draw nourishment from the ground. In most mountainous areas there is usually a clearly marked timberline, a boundary above which there is no tree growth. Sometimes the height of the timberline …

Cranes do not topple over because their jibs or booms are counter balanced at the opposite end from the the lifted load, thus keeping the center of gravity over the base. The first cranes were simply long poles fixed in the ground at an angle, with a pulley at the top through which passed a rope. They were called “cranes” …

Now how is that possible? The fact is, for a living creature to get a ‘shock’ there has to be a substantial flow of current through the body. However, there is barely any current running through the bird’s body for two reasons. Firstly, the bird not only forms a circuit with the wire, but it also offers a high resistance …