Suppose the smallest division on the scale of the timing device is t, the reaction time of a normal person os t', which one should be used for estimating the incertainty on the measurement of period T after a single timing activity? Explain briefly.

Answer 1

The reaction time delay, if always the same, will not affect the measurement of an intervsal of time, since it affects both the beginning and the end of the interval T in the same way. However, reaction time can vary from one measurement to another. I would estimate the rms variation in reaction time to be about t'/3, resulting in an interval measurement error of 0.47 t' and a total measurement error (standard deviation) of about sqrt(t^2 + 0.2 t'^2)

This is probably not the answer they are expecting. They probably want you to say t.