NCERT Science Class-VII Chapter-8: Winds, Storms and Cyclones Solutions

Exercises

1. Fill the missing word in the blank spaces in the following statements:

(a) Wind is __________ air.
(b) Winds are generated due to __________ heating on the earth.
(c) Near the earth’s surface __________air rises up whereas ___________ air comes down.
(d) Air moves from a region of __________ pressure to a region of __________ pressure.

Answer.

(a) Wind is moving air.

(b) Winds are generated due to uneven heating on the earth.

(c) Near the earth surface warm air rises up whereas cold air comes down.

(d) Air moves from a region of high pressure to a region of low pressure.

2. Suggest two methods to find out wind direction at a given place.

Answer. Two methods to find out wind direction at a given place:

(i) Take some sand and release it from height. The direction in which the sand starts flowing is the direction of the wind.
(ii) Take an air balloon and releases it in the open space. The balloon will starts moving in one direction which will give you an idea about the direction of the wind at that place.

3. State two experiences that made you think that air exerts pressure (other than those given in the text).

Answer. We can experience air pressure in our daily activities such as:

  1. Tree leaves and branches flutter due to pressure exerted by air in the form of wind.
  2. It is difficult to ride a bicycle against the wind but it is much easier in the direction of wind.

4. You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.

Answer. No, I would not like to buy a house having windows but no ventilators because the room will not able to cool down properly. Warm air is lighter which rises up and exit from the ventilators. Cool air is heavier and thus move in through window making the room comfortable for living. Ventilators are important for the circulation of air.

5. Explain why holes are made in hanging banners and hoardings.

Answer. Air exerts pressure in all directions. If banners and hoardings do not have holes, pressure exerted by wind may tear them off or make them fall. Holes let the air pass through and reduce the air pressure on banners and hoardings.

6. How will you help your neighbours in case cyclone approaches your village/town?

Answer. Ways to help the neighbours in case cyclone:

(i) Providing first aid to the injured ones.
(ii) Keeping them informed about the weather forecast, alerts and warnings.
(iii) Helping them in moving to the shelter.
(iv) Arrangement of food and drinking water.
(v) Informing the rescue operators, agencies and forces about the affected area in the locality.

7. What planning is required in advance to deal with the situation created by a cyclone?

Answer. Self-help is the best help. Therefore it is better to plan in advance and be ready with defense against any approaching cyclone. Planning required in advance to deal with cyclone-hit situation:

  1. Keep an emergency kit at home.
  2. Store enough food in water proof bags.
  3. Store safe drinking water as contaminated water can cause diseases.
  4. Keep phone numbers of emergency services like police, hospital, friends and relatives ready.
  5. Make necessary arrangements to shift the essential household goods, domestic animals and vehicles, etc. to safer places.

8. Which one of the following place is unlikely to be affected by a cyclone.
      (i) Chennai          (ii) Mangaluru (Mangalore)                 (iii) Amritsar               (iv) Puri

Answer. (iii) Amritsar

9. Which of the statements given below is correct?
(i) In winter the winds flow from the land to the ocean.

(ii) In summer the winds flow from the land towards the ocean.
(iii) A cyclone is formed by a very high-pressure system with very high-speed winds revolving around it.
(iv) The coastline of India is not vulnerable to cyclones.

Answer. (i) In winter the winds flow from the land to the ocean.

 

 

 

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