Question 2(d)(ii) Achieved

On a hot day the violin goes out of tune easily, and Sam has to adjust the tension in the "G" string to keep it vibrating at 196 Hz.

Explain how she might stop the wine glass from vibrating when she plays the violin.

The 2023 paper, page 5 ↗ Marking schedule, page 3 ↗

Work it out

Try it on paper first. Stuck? Take one hint at a time.

1. 1 The glass rattles because the driving frequency matches its natural frequency. What are the ways to break that?

   Make the two frequencies stop matching, or take energy out of the glass faster than the sound puts it in.

2. 2 How could you change the glass’s natural frequency?

   Change the glass: pour some water into it, which changes how it vibrates and so its natural frequency. Then 564 Hz no longer matches.

3. 3 How could you take the energy out?

   Damp it: stand it on something soft, such as a folded cloth or a cushioning mat, which absorbs the vibration. (Moving it away, or Sam avoiding that note, also works.)

What the marker wanted

• Achieved A practical way to stop the glass rattling.

The schedule marks (d)(i) and (d)(ii) together as one item. A way to stop the rattle is Achieved on its own; with the full explanation of resonance in (i), it completes the Excellence answer.

In our words, from NZQA’s 2023 marking schedule.

How did it go?

Got it moves it further out. Review brings it back tomorrow.