$${v = \sqrt{\frac{\tau}{\mu}} = \sqrt{\frac{\tau}{m/L}} = \sqrt{\frac{\tau L}{m}} \\ = \sqrt{\frac{(325\, \mathrm{N})(0,800\, \mathrm{m})}{2,50 \times 10^{-3}\, \mathrm{kg}}} = 322,49\, \mathrm{m/s}}$$