Twice a day, the sea rises and falls along most coastlines. Three separate forces, not one, actually cause this.
✊ Must Know
Three Forces Behind Every Tide
- Tides are caused by a combination of the Moon’s gravity, the Sun’s gravity, and centrifugal force from Earth’s rotation around the Earth-Moon and Earth-Sun barycenters.
- The Moon’s pull matters more than the Sun’s, even though the Sun is far more massive. Tidal force falls off with the cube of distance, and the Moon sits far closer.
- At new moon and full moon, the Sun and Moon align. Their pulls reinforce each other, producing extra-high ‘spring tides.’
- At the Moon’s first and third quarters, the Sun and Moon pull at right angles. Their forces partly cancel, producing smaller ‘neap tides.’
- The Bay of Fundy in Canada records the world’s largest tidal range, over 16 metres between high and low tide.
📝 Previous Year Questions
What Actually Causes Tides
- Three forces Tides result from the Moon’s gravity, the Sun’s gravity, and Earth’s own centrifugal force acting together, not any one force alone.
- Answer: (d) 1, 2 and 3 — all three forces contribute.
- View this question on the full 2015 paper →
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