The time, \(T\) seconds, it takes to swing back and forth once is \(T = 2\pi \sqrt {\dfrac{l}{g}} \), where \(l\,\text{m}\) is the length of the swing and \(g\) is the gravitational acceleration. Find \(T\), if \(l=2.45~\text{m}\) and \(g = 10~\text{ms}^{- 2}\)