An engineer investigates sound waves in a metal beam used in a bridge.
A vibration generator produces a steady wave in the beam at a frequency of 3.20 kHz3.20\ \text{kHz}3.20 kHz. A pickup connected to an oscilloscope is used to locate five consecutive nodes.
The table shows the distance between each pair of adjacent nodes.
| Pair of nodes | Distance between nodes in m\text{m}m |
|---|---|
| 1 and 2 | 0.77 |
| 2 and 3 | 0.78 |
| 3 and 4 | 0.77 |
| 4 and 5 | 0.78 |
Adjacent nodes are half a wavelength apart.
Calculate the speed of the wave in the metal beam.
The engineer increases the frequency of the vibration generator to 4.00 kHz4.00\ \text{kHz}4.00 kHz.
Calculate the predicted distance between adjacent nodes at this frequency.
The engineer sends a single pulse along 3.10 m of the beam. The travel time is measured using two methods.
| Timing method | Measured travel time |
|---|---|
| hand-operated stopwatch | 0.20 s |
| pickups connected to a data logger | 0.625 ms |
Explain which timing result is more suitable for determining the speed of the pulse.