Category Physics

The finer the water is sprayed on a fire, the faster it evaporates. As a result, it takes away energy from the flames and cools down the burning substance to such an extent that it can no longer catch fire again. Water extinguishes fire by creating a film of water over the burning substance, and thus cutting off its oxygen supply. Water has many advantages such as it is non-toxic in nature and is available in plenty. Water can be used to extinguish fire as discussed above, but this is not true in all cases of fire, for example, oil burning in a pan can be extinguished better by covering it with a lid rather than using water, burning metals would split the water chemically through the heat, and oxygen will be released which will intensify the fire further. Similarly, water cannot be used in cases where the fire has originated due to an electric fault. 

Unlike a petrol engine, an air – fuel mixture is not used in a diesel engine, but instead pure air is sucked in a cylinder. The air is compressed so strongly in the cylinder that it gets heated up to 700-900°C. The diesel fuel is then sprayed finely in this hot air and immediately gets ignited because of the high temperature. The expansion of combustion gases pushes a piston downwards. This force is transferred to the wheels of the car via shafts. The gases released in the combustion are discharged via the exhaust. 

The Latin word fossilis means ‘unearthed’ or ‘excavated’ because we need to excavate these fuels. In other words, they are buried deep inside the Earth and we need to dig them out. Fossil fuels are made of plants and animals that died millions of years ago and were converted – by the processes inside the Earth – into coal, crude oil, or natural gas. The energy stored in these fossils can be released and used by burning them. Searching for coal or crude oil, pumping out these fuels from the depths, and transporting them require a lot of effort and time. The crude oil must then be converted into petrol for cars. 

Coal is essentially made from dead plant material. Around 300 million years ago, in the Carboniferous period, huge ferns grew in the tropical climate and dead plants sank in the swamp. The dead plant layers forced oxygen out and left rich carbon deposits. The pressure of this layer pressed the water out of the remains of the plants slowly. This first gave rise to brown coal. Hard coal was formed when the pressure increased further. It is found in deeper layers and is a high-quality fuel. It is dug out in mines. Brown coal, on the other hand, is mined by using excavators.

By using acoustic or sound signals, the geologists identify the places where oil can occur on the Earth. They study these regions by looking in the rocky layers and taking samples at different depths. If the studies point to a deposit of oil, a hole is drilled in the ground in the hope of finding oil. Scientists believe that crude oil arose from the smallest sea organisms, the planktons. After dying, the planktons sank to the seabed and were covered with sand and sludge over a long period of time. Because of the high pressure exerted by this layer, the dead mass got converted into digested sludge, which gradually got converted into crude oil. Since oil is lighter than rock, it rose up and was held in pores of the rock, like water in a sponge. 

At places where crude oil is found, huge, hollow chisels drill several hundred metres deep in the Earth to reach the rocky layers containing oil. In some cases, the oil shoots out because of the pressure of the natural gas, which is found frequently with crude oil. Pumps are used to bring the oil to the surface if the pressure is not adequate. The oil is then transported to the big harbours with ships or through pipelines—hundreds of kilometres long. Sometimes it is also transported directly to a refinery, where it is processed further.