Physica A 287 (2000) 83–90 www.elsevier.com/locate/physa Energy dependence of impact fragmentation of long glass rods Emily S.C. Ching ∗ , S.L. Lui, Ke-Qing Xia Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong Received 19 June 2000 Abstract We have performed an experimental study of impact fragmentation with a focus on the dependence on the energy input. Long glass rods were dropped horizontally onto the ground from seven dierent heights. We nd that the energy dependence is better characterized by studying the dierential mass distribution rather than the cumulative mass distribution. For lower dropping heights, the dierential mass distribution is well approximated by one power law while for higher heights, it has to be represented by two power laws. Moreover, the power-law ex- ponent for small mass fragments increases and approaches an asymptotic value as the dropping height is increased. c  2000 Elsevier Science B.V. All rights reserved. PACS: 46.50.+a; 05.40.−a; 62.20.Mk 1. Introduction Fragmentation is a physical process that occurs commonly in everyday life and in many areas of science and technology. Examples include breaking of glasses at home and breaking of raw ore in mineral processing. In all situations, an object breaks up into many smaller pieces or fragments as a result of some external impact forces that impart a sucient amount of energy. In some cases we wish to prevent fragmentation from happening at all while in other cases we would like the object to be fragmented as thoroughly as possible. Fragmentation processes are complex and involve propagation of many cracks and their interaction. As a result, it is of interest to study the overall statistical aspects. One of the remarkable statistical features observed is the power-law distribution of the fragment mass. For example, in an experimental study of brittle fracture of glass * Corresponding author. Fax: +852-2603-5204. E-mail address: ching@phy.cuhk.edu.hk (E.S.C. Ching). 0378-4371/00/$ - see front matter c  2000 Elsevier Science B.V. All rights reserved. PII: S0378-4371(00)00446-5