We develop a detailed approach to study how mobilityimpacts the performance of reactive MANET routing protocols. In particular we examine how the statistics of path durations including PDFs vary with the parameters such as the mobility model, relative speed, number of hops, and radio range. We find that at low speeds, certain mobility models may induce multi-modal distributions that reflect the characteristics of the spatial map, mobility constraints and the communicating traffic pattern. However, our study suggests that at moderate and high velocities the exponential distribution with appropriate parameterizations is a good approximationof the path duration distribution for a range of mobility models. As an analytical case study, we then show how the mathematical expression obtained for the path duration distribution can be used to prove that the non-propagating cache hit ratio in DSR is independent of velocity for the freeway mobility model. The case study illustrates how various asp...