Author: Heba Soffar

The waves 0

The wave motion and the types of the waves

The waves The wave motion is an example of the periodic motion . It is very important to know that the wave is a disturbance that propagates and transfers the energy in the direction...

The dinosaurs extinction 0

The causes of the old and recent extinction

The scientists witnessed five mass extinctions , And some scientists believe that we live the sixth extinction age ( The Recent Extinction ) , where the rate of the extinction is 40 times larger...