Including end correction (total ≈0.6d for two open ends), effective length L+0.6d = v/(2f); solving 0.48+0.6d=0.5 m gives d ≈0.0333 m (3.33 cm).

Quality or timbre of sound depends on the presence and relative strengths of overtones (harmonics).

Sound requires a material medium to propagate; space is essentially a vacuum, so sound cannot travel there.

The OCR answer key indicates option B as the correct choice.

A frequency of 244 Hz gives |244−240|=4 beats and |252−244|=8 beats, matching both observations.

In a musical scale successive notes increase in frequency, which corresponds to increasing pitch.

The persistence of sound in an enclosed space due to multiple reflections is called reverberation.

At an interface frequency remains the same while speed and wavelength change, so frequency is unchanged.

Increasing amplitude raises loudness, and increasing frequency raises pitch, so loudness increases and pitch is raised.

Source speed v = ωr = 20×10 = 200 m/s. Minimum observed frequency (when receding) f' = f/(1 + v/v_sound) ≈ 320/(1+200/340) ≈ 200 Hz.