In a longitudinal wave, the motion of the medium is parallel to the direction of the wave. This means that the particles move left and right which in turn makes the other particles start to oscillate.
The UNIA founded by Marcus Garvey has a constitution which defines red, black, and green as the Pan-African colours: red representing the noble blood that unites all people of African ancestry, the colour black for the people, green for the rich land of Africa..
The white color is the symbol of harmony, brightness, and hope. In addition, it symbolizes the White Flag League, a patriotic faction which rebelled against the settlers in 1924. The black color is the symbol of the country itself; Sudan stands for black in Arabic language.