Dimensional analysis (DA) is a simple, elegant and intuitive method for determining the functional dependence of physical quantities relevant to a certain physical process. In other words, it is one of powerful widely applicable theoretical tools to reduce a complex physical system to a simpler form before their qualitative analysis of experimental investigation. Thus, the phenomenon under investigation can be described by a dimensionally correct equation among the variables . A dimensional analysis provides qualitative informatio0n about the model. It is especially important when it is necessary to conduct experiments in the modeling process. In this book we have attempted several uncommon and interesting problems to understand the involved physicswithout even solving the different equations not using calculus. DA has been applied suitably to allometric scaling, quantum mechanical problems, electrodynamics and astrophysics problems that are not often highlighted in a standard test book. A chapter has been devoted to discuss the breakdown of DA. This book for suitable for high-school students to post-graduate students who wish to pursue career in natural science. There are about more than 500 problems which are important for various competitive examinations such as JAM, NET, KVPY, NTSE, and GATE. The problems have been categorized for high school students, undergraduate and post graduate students. The students will be benefitted by solving these problems that will enhance their understanding students. The students will be benefitted by solving these problems that will enhance their understanding and motivate them to pursue estimation and modeling. This intriguing book of physics problems will not only be challenging but also be fun.