Type A Expmt Part 2 Exercise 2: Timer Measurement

a) Consider the stopwatch shown in the diagram. How would you record the measurement, with uncertainty, for the time shown?

(This is a Type B evaluation. Keep in mind that a stopwatch truncates.)

b) One member of your group is going to measure their reaction time using a stopwatch on their phone as follows:

• • You’re going to try to stop the timer at 10 s. Cover the last 3 digits so that when the timer hits 10.00 s the only thing you see is the initial 1.
  • Start the timer
  • When you see the 1, stop the timer
  • The difference between the time on the stopwatch and 10.00 s is your reaction time

Perform 5 trials and record the measurements.

c) Did you get the same result every time? It would be unusual if you did! Why?

The important thing to understand is that this random variation is intrinsic to the process of reaction – it is not a “mistake”, nor can it be eliminated. We will need to use a Type A evaluation on this data set…