Questions

A machine depreciates in value each year at the rate of 10% of its previous value. However, every second year there is some maintenance work so that in that particular year, depreciation is only 5% of its previous value. If at the end of the fourth year, the value of the machine stands at Rs 1,46,205, then find the value of machine at the start of the first year.

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The first working steam­ powered vehicle was designed and most likely built by Ferdinand Verbies, a Flemish member of a Jesuit mission in China around 1672. It was a 65 cm long scale­ model toy for the Chinese Emperor, that was unable to carry a driver or a passenger. It is not known if Verbiest's model was ever built. Nicolas- Joseph Cugnot is widely credited with building the first full­ scale, self ­propelled mechanical vehicle or automobile in about 1769; he also created a steam­ powered tricycle. He constructed two steam tractors for the French Army, one of which is preserved in the French National Conservatory of Arts and Crafts. His inventions were however handicapped by problems of water supply and maintaining steam pressure. In 1801, Richard Trevithick built and demonstrated his Puffing Devil road locomotive, believed by many to be the first demonstration of a steam ­powered road vehicle. It was unable to maintain sufficient steam pressure for long periods. Sentiment against steam ­powered road vehicles led to the Locomotive Acts of 1865. In 1807 Nicephore Niepce and his brother Claude probably created the world's first internal combustion engine which they called Pyreolophore.

Cugnot built steam tractors for:

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Crude mineral oil comes out of the earth as a thick brown or black liquid with a strong smell. It is a complex mixture of many different substances, each with its own individual qualities. Most of them are combinations of hydrogen and carbon in varying proportions. Such hydrocarbons are also found in other forms such as bitumen, asphalt and natural gas. Mineral oil originates from the carcasses of tiny animals and from plants that live in the sea. Over million of years, these dead creatures form large deposits under sea­bed and ocean currents cover them with a blanket of sand and silt. As this material hardens, it becomes sedimentary rock and effectively shuts out the oxygen, thus preventing the complete decomposition of the marine deposits underneath. The layers of sedimentary rocks become thicker, and heavier. Their pressure produces heat, which transforms the tiny carcasses into crude oil in a process that is still going on today.

Sedimentary rocks leads to the formation of oil deposits because

Drugs that combat depression work by

Lymph carries digested and absorbed fat from ______.

Which organelle performs cellular respiration?

What is the natural source of Oxalic acid?

What is the value of (2/√3 +tan45° ) ?