Tag: physics

The force which is perpendicular to the surface on which it is acted is called a thrust.

Thrust is a reaction force described quantitatively by Newton's second and third laws. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system.

Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.

The sun is the ultimate source of almost all kinds of energy on earth,

either directly or indirectly.
Directly sun gives us solar power and is perfect non-conventional energy source.
Moreover, Fossil fuels (coal, oil and gas) are the

transformed forms of plants (and animals) which once lived on the earth

and grew capturing the energy of the sun. Biomass is a product of

photosynthesis where the sun has the major role. Hydro-electricity

depends upon the water cycle which again is dependent on solar

radiation. Similarly, wind energy, tidal power, wave power all, in some

way or other, and depend on the sun.

Wind, water, tides all can be used again and again. But, once natural gas is burnt, it can never be used again.

Answer is D.

A non-renewable resource (also called a finite resource) is a resource that does not renew itself at a sufficient rate for sustainable economic extraction in meaningful human time-frames. An example is carbon-based, organically-derived fuel. The original organic material, with the aid of heat and pressure, becomes a fuel such as oil or gas. Earth minerals and metal ores, fossil fuels (such as coal, petroleum, and natural gas), nuclear fuels, and groundwater in certain aquifers are all non-renewable resources.
Natural resources such as coal, petroleum (crude oil) and natural gas take thousands of years to form naturally and cannot be replaced as fast as they are being consumed. Eventually it is considered that fossil-based resources will become too costly to harvest and humanity will need to shift its reliance to other sources of energy. 
Hence, fossil fuels are non-renewable resources.

Answer is A.

Carbon monoxide, nitrogen oxides, and hydrocarbons are released when fuel is burned in an internal combustion engine and when air/fuel residuals are emitted through the vehicle tailpipe. Gasoline vapors also escape into the atmosphere during refueling and when fuel vaporizes from engines and fuel systems caused by vehicle operation or hot weather.
The pollutants in vehicle emissions are known to damage lung tissue, and can lead to and aggravate respiratory diseases, such as asthma. Motor vehicle pollution also contributes to the formation of acid rain and adds to the greenhouse gases that cause climate change.
Pollutants emitted directly from vehicles are not the only cause for concern. On warm, sunny days, hydrocarbons react with oxides of nitrogen to create a secondary pollutant, ozone. In many urban areas, motor vehicles are the single largest contributor to ground-level ozone which is a common component of smog. Ozone causes coughing, wheezing and shortness of breath, and can bring on permanent lung damage, making it a cause of crucial public health problems.
Hence, CNG gas is used to control the air pollution. ompressed natural gas, or CNG, is natural gas under pressure which remains clear, odorless, and non-corrosive. Although vehicles can use natural gas as either a liquid or a gas, most vehicles use the gaseous form compressed to high pressures.

Hydrogen has the highest calorific value of 150 kJ/g. Among the hydrocarbon, methane has the highest calorific value of 55 kJ/g.