Science Q & A
From Wikibooks, the open-content textbooks collection
Q. How do trees reduce Air pollution?
A. Our atmosphere (air surrounding earth) contains Nitrogen 78%, Oxygen 21%, Carbon dioxide 0.03% and traces of other gases like helium, neon, ammonia, sulfur dioxide, nitrous and nitric oxide . Our atmosphere also contains aerosols, dust. Carbon dioxide is emitted when we burn fossil fuels which causes global warming. Trees absorb carbon dioxide and convert it into carbohydrates (in a process called photosynthesis) and ultimately wood. Thus they act as carbon bank and reduce carbon dioxide and global warming.
Dust and aerosols are stopped by trees foliage and thus they act as natural curtains. Tree leaves emit small amounts of water vapor into the air in a process called transpiration and coll down the atmosphere in the process. Wood and foliage of trees block sound and hence trees are plated on busy roads pavements, reduce noise pollution greatly. Thus trees are highly beneficial in combating pollution.
Q. Why does sunlight split into different colors when passed through a prism?
A. White light from sun is not a single color but a mixture of seven different colors (namely Violet, Indigo, Blue, Green, Yellow, Orange and Red). Each color has different wavelengths, Violet has wavelength of 380 nanometers whereas Red has a wavelength of 600 nanometers. When sunlight passes through a refractive medium like a prism each wavelength is refracted or bent to a different degree which is a function of their wavelength. Red get bent the least, Orange gets more than red and so on and violet gets bent the most. So these colors tend to split up when sunlight or white light is passed through prism. The process of light splitting up in a prism is called dispersion (see animation right).
Q. What is a nanometer?
A. Nanometer is one billionth of a meter. Or 10-9 of a meter. Or 
of a meter.
Q. How do rockets soar into sky?
A. Rockets rely on Newtons third law of motion which says 'every action has a equal and opposite reaction'. In rockets combustion chamber chemicals called propellants are burnt. Burning of propellants produce lot of hot gases which rush out of the rear. The action of gases rushing out of rockets rear causes reaction which is (propelling or) pushing the rocket forward.
