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..
Red, white, black and green are called the pan-Arab colors and have been historically linked to the Arab people and Islamic religion for centuries. The colors stand for Arab unity and independence. The red stripe represents Sudan's struggle for independence and the sacrifices of the country's martyrs.