Consider the following statements with reference to sea waves: 1. The height of waves is determined by wind speed, wind duration, and fetch 2. The energy of a wave is proportional to the square of its height 3. Waves retain most of their energy as they travel across the deep ocean Which of the statements given above is/are correct?
- (a)1 only
- (b)1 and 2 only
- (c)2 and 3 only
- (d)1, 2 and 3
Correct — D, 1, 2 and 3. All three statements are true. Statement 1: a wave's height is set by how hard the wind blows (wind speed), how long it blows (duration) and the fetch — the uninterrupted stretch of open water over which the wind acts. Statement 2: a wave's energy is proportional to the square of its height, so doubling the height quadruples the energy. Statement 3: in the open, deep ocean the water particles move in nearly closed circular orbits and very little energy is lost to friction, so a wave keeps most of its energy until it reaches shallow water near the coast. Hence all three hold.
- (a)1 only — It accepts only the wind-speed/duration/fetch rule and wrongly rejects the energy relationship and the deep-ocean persistence, both of which are also correct.
- (b)1 and 2 only — It correctly takes statements 1 and 2 but wrongly drops statement 3 — waves genuinely do retain most of their energy across the deep ocean.
- (c)2 and 3 only — It omits statement 1, yet wave height is indeed governed by wind speed, wind duration and fetch, so leaving it out is wrong.
A sea wave transports energy, not water: as a wave passes, water particles trace small near-circular orbits and return roughly to their starting point, so it is the energy that moves forward. The size of wind-generated waves grows with three inputs — wind speed, the duration for which the wind blows, and the fetch (the open-water distance over which it blows). Because friction losses in deep water are tiny, ocean swell can travel thousands of kilometres and still arrive with most of its energy, spending it only when it 'feels' the bottom and breaks near shore.
Each statement is a separate, well-established fact, so the safe approach is to test them one at a time rather than look for a single trap. All three are standard textbook results, which points to the 'all correct' option.
- Wave height depends on wind speed, wind duration and fetch (the open-water distance the wind blows over).
- Wave energy is proportional to the square of the wave height.
- Waves move energy, not the water body itself; particles move in near-circular orbits in deep water.
- In deep water friction losses are small, so waves retain most of their energy until they break in shallow water.
All three statements are correct, so the answer is 1, 2 and 3 — option (d).
- Waves carry energy, not water — do not think the water itself travels across the whole ocean.
- Energy scales with the square of height, not directly with height, so small height changes matter a lot.
Usually asked as a 'which statements are correct' set mixing the height controls (wind speed/duration/fetch) with the energy relationship and deep-water persistence.
No directly related past PYQ was found.
- practice — not a real PYQ
The uninterrupted distance of open water over which the wind blows to build waves is called the:
- (a)swash
- (b)fetch
- (c)wavelength
- (d)wave period
Answer(b) fetch — a longer fetch (with strong, prolonged wind) produces larger waves.
- practice — not a real PYQ
In deep water, as a wave passes, the water particles mainly:
- (a)move forward with the wave across the ocean
- (b)move in near-circular orbits and return close to their original position
- (c)sink permanently to the sea floor
- (d)remain completely still
Answer(b) move in near-circular orbits and return close to their original position — the energy travels, the water does not.