You have been presented with a source of electrons, ${ }^{14} \mathrm{C}$, having kinetic energy equal to 0.305 times the rest energy. Suppose you have a pair of detectors that can detect passage of the electrons without disturbing them. You wish to show that the relativistic expression for momentum is correct and the nonrelativistic expression is incorrect. If a $2.0-\mathrm{m}$ -long baseline between your detectors is used, what is the necessary timing accuracy needed to show that the relativistic momentum is correct?