紙片在空氣中落下的運動行為是一個非常複雜的現象。有時候它看起來是那麼的不規則，然而有時看起來似乎是有其規則性。過去關於紙片落下的相關研究不管是在理論計算或是實驗觀察幾乎都是在二維的環境下進行。在本論文裡，我們將在一般的空氣中以實驗的方式觀察紙片落下時的運動現象。如此即可觀察到紙片在三維空間中的運動行為。我們將紙片的水平放置，再使其自由落下，並有系統地觀測不同長寬尺寸的紙片自由落下時的運動。我們主要的研究重點在於（1）紙片落下時的運動種類（2）長方形紙片在不同方向上選擇情形（3）正方形紙片在轉動過程中，其轉軸在平行軸與對角軸的選擇性。 The motions of a falling paper in air are very complex appearance. Sometimes a falling paper’s motion may seem to be random. However, it could also be regular. In the past theoretical and experimental studies about falling paper most were in 2-D condition. In this thesis, we investigate experimentally falling paper in open air. Extensive 3D motions are observed. By setting the paper in the horizontal orientation initially, we systematically observe the 3-D behaviors of falling paper with different sizes and weights. Our main results include (1) The types of behaviors, e.g., rotational or fluttering, could depend on the initially releasing angles, (2) the selections of flutter motions in different directions for rectangular papers, and (3) the selections between rotations about parallel axis and diagonal axis for square papers.
