GS PrelimsGeography (Physical)Ocean Water Movement2015

Tides occur in the oceans and seas due to which among the following? 1. Gravitational force of the Sun 2. Gravitational force of the Moon 3. Centrifugal force of the Earth Select the correct answer using the code given below.

A

1 only

B

2 and 3 only

C

1 and 3 only

D

1, 2 and 3

Correct Answer: Option D

Explanation

1. Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun, and the rotation of the Earth. 2. Statement 1: The Gravitational force of the Sun exerts a pull on the Earth's oceans, contributing to the tidal bulge. Although the Sun is much more massive than the Moon, its greater distance means its tide-generating force is less than half that of the Moon. It is a contributing factor. Hence, Statement 1 is correct. 3. Statement 2: The Gravitational force of the Moon is the primary driver of tides. Its proximity to the Earth results in a stronger differential gravitational pull across the Earth, creating tidal bulges on the sides facing and opposite the Moon. Hence, Statement 2 is correct. 4. Statement 3: As the Earth-Moon system rotates, there's an outward-flinging force, often conceptualized as the centrifugal force, acting on the Earth's water. This force contributes to the tidal bulge on the side of the Earth opposite the Moon (balancing the gravitational pull towards the Moon on the near side). Therefore, the rotation of the Earth (and the resulting apparent centrifugal force) is also a factor in creating the two tidal bulges. Hence, Statement 3 is correct. 5. All three factors – the gravitational forces of the Sun and Moon, and the centrifugal force associated with the Earth's rotation (within the Earth-Moon system) – contribute to the occurrence of tides.

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