The Kinematics of a Falling Dipterocarpus Alatus Seed

Abstract

Dipterocarpus Alatus (Thai:ยางนา, Yang Na ) is a tree found in Thailand and other Southeast Asian countries. The seeds have two wings and rotate as they fall. High-speed video analysis was used to determine the terminal velocity and spin frequency as a function of the mass of a seed. Values of wing velocity, lift force, and drag force were then determined. It was found that as the mass of the seed increased, terminal velocity, frequency, and lift force also increased. It was shown that 80-95% of the retarding force generated during the fall was from lift and that the coefficient of lift for the seed used was approximately 1.5.

Keywords

• Dipterocarpus Alatus
• seed
• mass
• terminal velocity
• lift force
• coefficient of lift