Abstract: From the perspective of rigid body mechanics and aerodynamics，this paper

has carried out theoretical analysis and certain experimental verification on the 17th

question " Playing Card" of the international Young Physicists Championship 2020 ( IYPT2020)

，and worked out a trajectory equation of a rotating card. Some rules of card’s movement

are discussed through parameter analysis. It is found that the main force affecting the

movement of card is the air resistance on the lower surface，which on the one hand

causes the precession of the card，on the other hand，produces the component force in three

directions through the precession，thus affecting the trajectory of the card.Finally，this paper

verifies the rationality of the theory by a self-designed card launcher.

Key words: IYPT, rotating rigid body, flat-plate flow, precession