What surprises me about ancient beliefs systems is how they different point of views
The answer is to the ground.
Gravity refers to the force that holds together the universe. On Earth, the gravity attempts to change the velocity of all the objects on the Earth's surface toward the ground at a rate of 9.8 meters per second squared according to Galileo.
Assuming the two functions are sine functions.
From the problem:
T = 1.5
So
b = 2π/T
b = 2π/1.5
b = 4π/3
The first sine function has an equation
y1 = sin 4π/3x
and since they have a difference in phase of π/6, the other sine function has an equation
y2 = sin 4π/3x + π/6
Their difference is simply π/6.
If we substitute 0.5 s to each equation,
y1 = 2π/3
y2 = 5π/6