The wavelength of middle C on a piano depends on the speed of sound, which varies with temperature and other factors. However, we can calculate an approximate value assuming standard room temperature (20°C) and a speed of sound of 343 m/s.

Here's how to calculate it:

1. Frequency of middle C: Middle C has a frequency of 261.63 Hz.

2. Formula: Wavelength (λ) = Speed of sound (v) / Frequency (f)

3. Calculation: λ = 343 m/s / 261.63 Hz ≈ 1.31 meters

Therefore, the approximate wavelength of middle C on a piano at room temperature is 1.31 meters.