A tuning fork, vibrating with a frequency of 90 Hz, is moving towards an observer with a with a speed of 0.1 times the speed of sound. The frequency of the note heard by the observer would be:

A tuning fork, vibrating with a frequency of 90 Hz, is moving towards

1.	A tuning fork, vibrating with a frequency of 90 Hz, is moving towards an observer with a with a speed of 0.1 times the speed of sound. The frequency of the note heard by the observer would be:
A.	80 Hz
B.	90 Hz
C.	100 Hz
D.	120 Hz
Answer» D. 120 Hz