14 A driver is playing loud music in a car travelling along a road at 100 km/h, the music has a constant frequency of 400 Hz. What frequency will a stationary observer hear as the car approaches the observer? Speed of sound = 340 m s". Select one alternative: O 367 Hz Q 465.3 Hz O 435.6 Hz O 381.5 Hz O 400 Hz Reset Maximum marks: 113 The diagram below shows two waves. Which statement Is correct? Select one alternative: O They have the same amplitude and differ in phase by 90'. O They have different amplitudes and differ in phase by 180*, O They have different amplitudes and differ in phase by 90". O They have the same amplitude and are in phase. They have the same amplitudes and differ in phase by 180.15 John is moving in front of two loudspeakers that produce the same frequency sound. He hears an alternating increase and decrease in the level of sound. Which of the following statements is correct? Select one alternative: O Sound wave from the two speakers only form constructive interference. O The increase in level of sound is caused by the destructive interference of the two sound waves. O Sound waves from the two speakers form an interference pattern. O The alternating increase and decrease in the level of sound is caused by the distance between John's ears. O The decrease in level of sound is caused by the constructive interference of the two sound waves. Reset Maximum marks: 1