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 flag of Uganda was adopted in 1962. The black color identifies Uganda as a black nation of Africa, the yellow represents the abundant sunshine Uganda enjoys being situated on the equator, and the red represents Uganda's brotherhood with the rest of Africa and the world.