The correct option is Centrifugal force..
Explanation
Tides are the rhythmical rise and fall of ocean water caused by the combined effects of gravitational forces exerted by the Moon and the Sun, alongside the rotation of the Earth. At any given time, two tidal bulges form on the Earth's surface: one facing the Moon and one on the side directly opposite to it.
Mechanism of Tidal Bulges
- First Bulge (Facing the Moon): The gravitational attraction of the Moon is the primary force responsible for the tidal bulge on the side of the Earth facing the Moon. The water is pulled towards the Moon.
- Second Bulge (Opposite Side): The Earth and the Moon rotate around a common center of mass. This rotation generates a centrifugal force that acts outwards. On the side of the Earth opposite to the Moon, the Moon's gravitational pull is at its weakest due to the increased distance. Consequently, the centrifugal force exceeds the gravitational attraction, causing the water to bulge outwards away from the Moon.
Analysis of Incorrect Options
- Gravitational attraction of the sun: While the Sun influences the magnitude of tides (creating Spring and Neap tides), it is not the specific cause of the second bulge located opposite the Moon.
- Gravitational attraction of the earth: Earth's gravity acts to hold water to the surface; it does not create an outward bulge.
- Coriolis force: This force deflects the direction of moving fluids (winds and currents) due to Earth's rotation but is not responsible for the vertical rise of tides.
Key Takeaway: The tidal bulge facing the Moon is generated by gravitational attraction, whereas the tidal bulge on the opposite side is generated by the centrifugal force of the Earth-Moon system.