Solutions to the 25th & 26th International Young Physicists' Tournament provides original, quantitative solutions in fulfilling seemingly impossible tasks. The book expands on the solutions required by the problems. Many of the articles include modification, extension to existing models in references, or derivation and computation based on fundamental physics, and are not confined to the models and methods in present literatures.The International Young Physicists' Tournament (IYPT) is one of the most prestigious international physics contests among high school students. This book is based on the solutions of 2012 and 2013 IYPT problems. The young authors provide quantitative solutions to practical problems in everyday life, such as the 2013 problem “Bouncing ball” that shows “how the nature of the collision changes if the ball contains liquid”, “Colored plastic” (2013 problem 6) and “Helmholtz carousel” (2013 problem 12) etc.This book is intended as a college-level solutions guide to the challenging open-ended problems. It is a good reference book for undergraduates, advanced high-school students, physics educators and the curious public interested in the intriguing phenomenon encountered in daily life.