Author Question: You are standing on a platform and a train approaches you, moving at a constant velocity. Its ... (Read 96 times)

wenmo · **on:** Jul 28, 2018

You are standing on a platform and a train approaches you, moving at a constant velocity. Its whistle is blowing continuously. The train does not stop at the platform, but it continues to move past the platform at a constant velocity. Which of the following statements are true about the frequency of the train's whistle that you hear?
1.The whistle's frequency that you hear increases continually as the train approaches the platform and then decreases continually after the train passes the platform.
2.The whistle's frequency that you hear seems to you to remain constant for the entire duration of the train's passage.
3.The whistle's frequency that you hear decreases continually as the train approaches the platform and then increases continually after the train passes the platform.
4.The whistle's frequency that you hear remains constant as the train approaches the platform and then decreases immediately after the train passes the platform, after which it remains constant at a lower pitch than it had originally.

Question 2

Two sounds of the same intensity are added together. The intensity of the resulting sound is how many decibels greater than the intensity of one of the original sounds? The resulting sound
1.will have twice the decibel level as one of the original sounds.
2.will have the same decibel level as one of the original sounds.
3.will be two decibels higher than the original sound.
4.will be three decibels higher than the original sound.