4. A train is blowing its whistle at while travelling at a speed of 33.0m/s. The speed of sound is 343m/s. Observer A is directly in front of the train, while observer B is directly behind it. How many times larger is the whistle frequency heard by A compared to that heard by B? (1.21) 5. When sodium gas is heated, it glows and gives off light waves. An astronomer on Earth observes sodium light waves coming from a distant galaxy. The true frequency for sodium light waves is 5.171014Hz The astronomer measures the sodium light coming from the galaxy and finds that its frequency, as it appears to us on Earth, is 4.701014Hz. If the speed of light is 3.00108m/s, what is the speed of the galaxy relative to us? Is it moving toward or away from us? (3.0107m/s away from us)