Question

High and low tides are the regular pattern of rising and sinking ocean-water levels. They are caused when the sun's gravity and the moon's gravity pull on ocean water. The moon's gravity has a greater effect on Earth's oceans than the sun's gravity. Why would the moon have a greater effect than the sun?
A. The moon is not as hot as the sun.
B. The moon has less mass than Earth.
C. The moon has less mass than the sun.
D. The moon is closer to Earth than the sun.

Answer 1

Answer:

D. The moon is closer to Earth than the sun.

Explanation:

Tides are formed as a consequence of the differentiation of gravity due to the moon across to the Earth sphere.

Since gravity variate with the distance:

   

$F = G\frac{m1\cdot m2}{r^{2}}$  (1)                            

Where m1 and m2 are the masses of the two objects that are interacting and r is the distance

For example, see the image below, point A is closer to the moon than point b and at the same time the center of mass of the Earth will feel more attracted to the moon than point B. Therefore, that creates a tidal bulge in point A and point B.

The Sun tidal force contributes to the tidal force of the moon over the earth making high tides higher and low tides lower.  

However, even when the sun is more massive than the moon, it is farther away from the Earth than the moon. So, it is clear by equation 1 that the moon's gravity has a greater effect on Earth's oceans than the sun's gravity.