An engineer investigates how fast a sound pulse travels along a steel rail. Two pickups detect the pulse as it passes.
In the current arrangement, the pickups are connected to an oscilloscope that electronically records both signals. In the proposed arrangement, the engineer watches indicators connected to the pickups and manually starts and stops a stopwatch when the indicators light.
| arrangement | separation of pickups | timing equipment | smallest time interval shown | measured time delay |
|---|---|---|---|---|
| current | 12.0 m | oscilloscope | 0.10 ms | 2.4 ms |
| proposed | 30.0 m | manually operated stopwatch | 0.01 s | not measured |
The sound pulse travels at the same speed in both arrangements.
Calculate the time delay expected when the pickups are 30.0 m apart.
Evaluate whether the proposed arrangement would reduce the percentage uncertainty in the measured time compared with the current arrangement. Use your answer to (a).