The diagram shows a stationary meteorological receiver, R, and a moving weather drone, D.
D emits a constant acoustic tracking signal. R detects this signal. D is moving at a constant speed in the direction shown by the arrow, directly away from R.
D emits a sound wave with a wavelength of 0.154 m. R detects this sound wave with a wavelength of 0.178 m.
Calculate the difference between the wavelength emitted by D and the wavelength detected by R.