Dimensional analysis is a powerful tool with several applications, including checking dimensional consistency of equations, deriving relationships between physical quantities (up to a dimensionless constant), and converting units between different systems. However, a key limitation is that it cannot determine the value of dimensionless constants. For example, in the formula for the period of a simple pendulum, $T = 2\pi \sqrt{l/g}$, dimensional analysis can only determine that $T \propto \sqrt{l/g}$, but it cannot determine the value of $2\pi$.