Answer:
New moon
Explanation:
A solar eclipse can only take place at the phase of new moon, when the moon passes directly between the sun and Earth and its shadows fall upon Earth's surface.
Answer:
f'=5.58kHz
Explanation:
This is an example of the Doppler effect, the formula is:
Where f is the actual frequency, 
is the observed frequency, 
is the velocity of the sound waves, 
the velocity of the observer (which is negative if the observer is moving away from the source) and 
the velocity of the source (which is negative if is moving towards the observer). For this problem:
