Water Class 7 Worksheet Geography Chapter 5

Q.1. What is a terrarium?

It is an artificial enclosure for keeping small house plants.

Q.2. What is the effect of high tide?

It is high tide when water covers much of the shore by rising to its highest level.

Q.3. What is the first indication of a tsunami?

The first indication that tsunami is approaching is the rapid withdrawal of water from the coastal region, followed by destructive wave.

Q.4. Where does the word tsunami come from and what does it mean?

Tsunami is a Japanese word that means “Harbour waves” as the harbours get destroyed whenever there is tsunami.

Q.5. What is water cycle?

The process by which water continually changes its form and circulates between oceans, atmosphere and land is known as the water cycle.

Q.6. What are the factors affecting the height of the waves?

During a storm, the winds blowing at very high speed form huge waves. An earthquake, a volcanic eruption or underwater landslides can shift large amounts of ocean water. As a result a huge tidal wave called tsunami, that may be as high as 15m., is formed.

Q.7. What are the major movements of ocean water?

The movements that occur in oceans can be broadly categorised as: waves, tides and currents.

Waves - When the water on the surface of the ocean rises and falls alternately, they are called waves. Waves are formed when winds scrape across the ocean surface. The stronger the wind blows, the bigger the wave becomes.

Tides - The rhythmic rise and fall of ocean water twice in a day is called a tide. It is high tide when water covers much of the shore by rising to its highest level. It is low tide when water falls to its lowest level and recedes from the shore. The strong gravitational pull exerted by the sun and the moon on the earth’s surface causes the tides.

Ocean Currents - Ocean currents are streams of water flowing constantly on the ocean surface in definite directions. The ocean currents may be warm or cold. Generally, the warm ocean currents originate near the equator and move towards the poles. The cold currents carry water from polar or higher latitudes to tropical or lower latitudes. The Labrador Ocean current is cold current while the Gulf Stream is a warm current.

Q.8. Why are tides important to us?

Tides important to us because:-

• High tides help in navigation.
• They raise the water level close to the shores. This helps the ships to arrive at the harbour more easily.
• The high tides also help in fishing. Many more fish come closer to the shore during the high tide. This enables fishermen to get a plentiful catch.
• The rise and fall of water due to tides is being used to generate electricity in some places.

Q.9. What are tides and how are they caused?

The rhythmic rise and fall of ocean water twice in a day is called a tide. The strong gravitational pull exerted by the sun and the moon on the earth’s surface causes the tides.

Q.10. What is precipitation?

Precipitation is any type of water that forms in the Earth's atmosphere and then drops onto the surface of the Earth.

Q.11. What is Tsunami?

Tsunami is a series of huge tidal waves caused by earthquakes or other disturbance under the sea.

Q.12.  What are the major sources of freshwater?

The major sources of fresh water are the rivers, ponds, springs and glaciers.

Q.13. Why is the ocean salty?

The water of the oceans is salty or saline as it contains large amount of dissolved salts.

Q.14. What are spring and neap tides?

The water of the earth closer to the moon gets pulled under the influence of the moon’s gravitational force and causes high tide. During the full moon and new moon days, the sun, the moon and the earth are in the same line and the tides are highest. These tides are called spring tides. But when the moon is in its first and last quarter, the ocean waters get drawn in diagonally opposite directions by the gravitational pull of sun and earth resulting in low tides. These tides are called neap tides.

Q.15. Write a short note on Tsunami?

Tsunami

• Tsunami is a Japanese word that means “Harbour waves” as the harbours get destroyed whenever there is tsunami.
• An earthquake, a volcanic eruption or underwater landslides can shift large amounts of ocean water.
• As a result a huge tidal wave called tsunami, that may be as high as 15m., is formed. The largest tsunami ever measured was 150m. high. These waves travel at a speed of more than 700 km. per hour.
• The tsunami of 2004 caused wide spread damage in the coastal areas of India. The Indira point in the Andaman and Nicobar islands got submerged after the tsunami.