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Tuesday, September 30, 2014

The effect of the extinction on the ecological equilibrium


It is very important to know that the Ecosystem is everything that related to the living and non-living things existing somewhere , for example the forest , the desert and the sea . In any ecosystem .

Monday, September 1, 2014

The types of the sound waves

 
The sound range

You should know that there are two types of the sound waves which are the audible sounds and the non - audible sounds .

 

The audible sounds such as the sonic waves , And the non - audible sounds such as the ultrasonic waves and the infrasonic waves .