(i) Which was the first metal used by man?
(a) Manganese
(b) Gold
(c) Copper
(d) Iron
Ans: (c)
Metals were discovered and starts using approximately 5000 years ago. First metal to be used was the copper. Then after silver and gold. These metals were found in free state in nature.
(ii) The energy we get from water is called
(a) nuclear energy
(b) solar energy
(c) hydro energy
(d) none of these
Ans: (c)
Hydropower, or hydro energy, is a form of renewable energy that uses the water stored in dams, as well as flowing in rivers to create electricity in hydropower plants.
(iii) The diesel engine was invented by
(a) Rudolf Diesel
(b) Gottlieb Daimler
(c) Alessandro Volta
(d) None of these
Ans: (a)
In the 1890s, Rudolf Diesel invented an efficient, compression ignition, internal combustion engine that bears his name.
(i) Electricity produced by running water is called _________.
Ans: Electricity produced by running water is called hydro-electric power.
The electricity produced by the flowing water is known as hydro-electric power. The water in a dam is allowed to fall on the turbine. As a result of this, turbines rotate whose axle is connected to the armature of the generator.
(ii) Iron tools are stronger than those made of _______.
Ans: Iron tools are stronger than those made of bronze tools.
Repeated heating and hammering made iron tools much stronger than bronze tools.
(ii) What were man’s earliest tools? What were these made of?
Ans: The earliest stone toolmaking developed by at least 2.6 million years ago. The Early Stone Age began with the most basic stone implements made by early humans. These Oldowan toolkits include hammerstones, stone cores, and sharp stone flakes.
(iii) How can electricity be produced?
Ans: Electricity is also produced from renewable sources such as wind, hydropower, solar power, biomass, wind, and geothermal. Together, renewable energy sources generated about 20% of the country's electricity in 2020. To produce electricity, a turbine generator set converts mechanical energy to electrical energy.
(iv) Name at least two sources of energy.
Ans: Sources of energy can be classified into:
(v) What is a machine?
Ans: A machine is a thing that is created by people to make work easier. It is a tool or invention which multiplies the effect of human effort. The machine produces a mechanical advantage.
(vi) What products come out of petroleum?
Ans: These petroleum products include gasoline, distillates such as diesel fuel and heating oil, jet fuel, petrochemical feedstocks, waxes, lubricating oils, and asphalt.
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1. What is the Machine Age? |
2. What were the main technological advancements during the Machine Age? |
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