A truck horn emits a frequency of 800 Hz in 20 °C air, which has a speed of sound of 343 m/s. If the truck is moving toward a stationary observer at 20 m/s answer the following: a) What is the frequency of the source (Hz) f(source)? b) What is the speed of sound v(m/s)? c) What is the speed of the observer (m/s) v(observer)? d) What is the speed of the source (m/s) v(source)? e) What is the frequency (Hz) that is observed f(observed)?