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..
SYMBOLIC MEANINGS OF COLORS. Black derives its significance from the notion that new things get darker while they mature; and physical aging comes with spiritual maturity. The Akans blacken most of their ritual objects to increase their spiritual potency.