Travelling towards a cliff, a car moves with a speed of 54 km h ⁻¹ . The car's horn emits sound at a frequency of 400 Hz , and the speed of sound is 335 m s ⁻¹ . Determine the wavelength of the sound emitted by the horn in the region in front of the car.

Step-by-step solution

Speed of the car, v_s = 54 km h ⁻¹ = 54 5 18 m s ⁻¹ = 15 m s ⁻¹ Frequency of the horn, f = 400 Hz Speed of sound, v = 335 m s ⁻¹ The wavelength of the sound in the region in front of the moving car is the apparent wavelength due to the source moving towards the observer. It is given by: ' = v - v_s f Substituting the given values: ' = 335 - 15 400 ' = 320 400 m ' = 0.8 m = 80 cm