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..
Colors represent different things to the Zulu people, and they use them symbolically in their art and fashion. The Zulu flag is blue, yellow, red and black. Each color has a positive and negative meaning attached to it.