Final answer:
The contribution of the Sun and the Moon to tides is compared by taking the ratio of their accelerations due to gravity. The Moon's greater tidal effect is due to the larger fractional change in distance from the near side to the far side compared to the Sun. This is why the tides are predominantly due to the Moon.
Step-by-step explanation:
The contribution of the sun to ocean tides can be compared to the contribution of the moon by taking the ratio of their respective accelerations due to gravity. The magnitude of the acceleration due to gravity at Earth due to the Sun can be calculated using the formula g = GM/R^2, where G is the gravitational constant, M is the mass of the Sun, and R is the distance between the Earth and the Sun. By dividing the Moon's acceleration due to gravity by the Sun's acceleration due to gravity, we can determine their relative contributions to the tides.
While the forces exerted by the Sun on the Earth are much greater than those exerted by the Moon, the difference in their forces is smaller for the Sun due to the smaller fractional change in distance from the near side to the far side of the Sun compared to the Moon. This is why the tides are predominantly due to the Moon, even though the Sun has much greater forces.