A student investigates how a plastic ruler vibrates when clamped to the edge of a desk. She presses the free end of the ruler down and releases it. This causes the ruler to vibrate and emit a sound. She uses a microphone connected to an oscilloscope to monitor the sound.
Explain what is meant by the pitch of a sound.
The student measures the vibrating length of the ruler and the frequency of the electrical signal from the microphone.
Name two instruments that she needs to obtain these measurements.
Identify the dependent variable and the independent variable in this investigation.
The student collects the following data:
| Vibrating length of ruler (cm\text{cm}cm) | Frequency of signal (Hz\text{Hz}Hz) |
|---|---|
| 25 | 35 |
| 20 | 55 |
Suggest three ways in which the student could improve her investigation.