Acceleration due to gravity.
Answer:
The second system must be set in motion
seconds later
Explanation:
The oscillation time, T, for a mass, m, attached to spring with Hooke's constant, k, is:

One oscillation takes T secondes, and that is equivalent to a 2π phase. Then, a difference phase of π/2=2π/4, is equivalent to a time t=T/4.
If the phase difference π/2 of the second system relative to the first oscillator. The second system must be set in motion
seconds later
Range, Belt.
Just got it right on e,,d,,g,,e
The amount of energy the Sun radiates into space and the amount of energy that reaches Earth.