Answer:
The earth's pull on the moon
Explanation:
Earth exerts a gravitational pull on the moon 80 times stronger than the moon's pull on the Earth.
Inertia- a tendency to do nothing or to remain unchanged
If the two waves have the SAME FREQUENCY and are exactly
out of phase (180° apart), then the resultant wave will have the
same frequency and an amplitude of 1 unit.
If the two waves do not have the SAME FREQUENCY, then their
relative phase is meaningless.