# IAS Prelims Exam: Physical Geography NCERT Questions: MOVEMENTS OF OCEAN WATER

Jagran Josh

For the Civil Services IAS Exam Geography has vast and it covers most sections of the General Studies for the IAS Prelims Exam. The geography is scientific in its orientation and hence the IAS Aspirants having Arts background find it very difficult to prepare the geography for the IAS Prelims Exam

Q1. Consider the following statements
1.  Movement of ocean water is influenced by physical characteristics of water.
2.  Tides refer to horizontal motion of ocean water.

Select the correct answer from the following codes
a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Explanation:
ocean water is dynamic. Its physical characteristics like temperature, salinity, density and the external forces like of the sun, moon and the winds influence the movement of ocean water. The horizontal and vertical motions are common in ocean water bodies. The horizontal motion refers to the ocean currents and waves. The vertical motion refers to tides.

Q2. Consider the following statements
1. Water in the wave’s moves from one place to another.
2. Upwelling of cold water and Tides are vertical motion of ocean water.

Select the correct answer from the following codes
a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Explanation:
Water moves ahead from one place to another through ocean currents while the water in the waves does not move, but the wave trains move ahead. The upwelling of cold water from subsurface and the sinking of surface water are also forms of vertical motion of ocean water.

Q3. With reference to waves, which of the following is/are true?
1. Waves are water which moves across the oceans.
2. Wave slows down as it approaches the beach.
3. The largest waves are found in the open oceans.
Select the correct answer from the following codes
a.    Only 1
b.    Only 1 and 2
c.    Only 2 and 3
d.    1,2 and 3

Explanation:
Waves are actually the energy, not the water as such, which moves across the ocean surface. Water particles only travel in a small circle as a wave passes. As a wave approaches the beach, it slows down. This is due to the friction occurring between the dynamic water and the sea floor. The largest waves are found in the open oceans. Waves continue to grow larger as they move and absorb energy from the wind.

Q4. Consider the following statements
1. Steep waves are formed by local winds.
2. Slow and steady waves originate possibly from other hemisphere.

Select the correct answer from the following codes
a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Explanation:
A wave’s size and shape reveal its origin. Steep waves are fairly young ones and are probably formed by local wind. Slow and steady waves originate from far away places, possibly from another hemisphere. The maximum wave height is determined by the strength of the wind, i.e. how long it blows and the area over which it blows in a single direction.

Q5. Consider the following statements
1. Tide is periodical rise and fall of sea level.
2. Surge is movement of water by meteorological effects.

Select the correct answer from the following codes
a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Explanation:
The periodical rise and fall of the sea level, once or twice a day, mainly due to the attraction of  the sun and the moon, is called a tide. Movement of water caused by meteorological effects (winds and atmospheric pressure changes) are called surges. Surges are not regular like tides.

Q6. Which of the following forces causes tide to greater extent?
1. Sun’s gravitational pull
2. Moon’s gravitational pull
3. Centrifugal force

Select the correct answer from the following codes
a.    Only 2
b.    Only 1 and 2
c.    Only 2 and 3
d.    1,2 and 3

Explanation:
The moons gravitational pull to a great extent and to a lesser extent the sun’s gravitational pull, are the major causes for the occurrence of tides. Another factor is centrifugal force, which is the force that acts to counter the balance the gravity.

Q7. Consider the following statements
1. The tidal bulges on narrow continental shelves, have greater height.
2.Intensity of tides are also influenced by shape of bays and estuaries.

Select the correct answer from the following codes
a. Only 1
b. Only 2
c. Both 1 and 2
d. Neither 1 nor 2

Explanation:
The tidal bulges on wide continental shelves, have greater height. When tidal bulges
hit the mid-oceanic islands they become low. The shape of bays and estuaries along a coastline can also magnify the intensity of tides. Funnel-shaped bays greatly change tidal magnitudes. When the tide is channelled between islands or into bays and estuaries they are called tidal currents.

Q8. Which of the following is/are true about spring tides?
1. Spring tides occur 4 times a month.
2.  Height of the spring tide is highest when sun, earth and moon are in straight line.
3. In spring tides, moons attraction dominates the counteracting gravitational pull of sun

Select the correct answer from the following codes
a.    Only 1
b.    Only 1 and 2
c.    Only 2 and 3
d.    1,2 and 3

Explanation:
In  Spring tides the position of both the sun and the moon in relation to the earth has direct bearing on tide height. When the sun, the moon and the earth are in a straight line, the height of the tide will be higher. These are called spring tides and they occur twice a month, one on full moon period and another during new moon period.

Q9. Which of the following is/are true about neap tides?
1.  Forces of sun and moon counteract each other.
2.  There is 14 days interval between spring and neap tide.
3. During aphelion and apogee the tidal range is higher than the average tides.

Select the correct answer from the following codes
a.    Only 1
b.    Only 1 and 3
c.    Only 2 and 3
d.    1,2 and 3

Explanation:
there is a seven day interval between the spring tides and neap tides. At this time the sun and moon are at right angles to each other and the forces of the sun and moon tend to counteract one another. Once in a month, when the moon’s orbit is closest to the earth (perigee), unusually high and low tides occur. During this time the tidal range is greater than normal. When the earth is farthest from the sun (aphelion), around 4th July each year, tidal ranges are much less than average.

Q10. Which of the following is/are true about importance of tides?
1. Tidal heights help ships to enter harbour.
2.  Remove polluted water from river estuaries.
3.  Tides also help in desilting sediments.

Select the correct answer from the following codes
a.    Only 1
b.    Only 1 and 2
c.    Only 2 and 3
d.    1,2 and 3