A vibration generator produces a short wave pulse at one end of a metal rod. The pulse travels along the rod to a sensor at the other end.
The table shows the displacement of one particle in the rod as the pulse passes. A positive parallel displacement is towards the sensor and a negative parallel displacement is away from the sensor.
| Stage | Displacement parallel to the rod in μm\mu\text{m}μm | Displacement perpendicular to the rod in μm\mu\text{m}μm |
|---|---|---|
| before the pulse arrives | 0 | 0 |
| first measurement | +2.0 | 0 |
| second measurement | 0 | 0 |
| third measurement | -2.0 | 0 |
| after the pulse has passed | 0 | 0 |
Explain what the measurements show about the type of wave in the rod, whether particles of the rod travel to the sensor, and how energy reaches the sensor.