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CBSE Board NCERT Solutions for Class 7th Science Chapter7:Winds, Storms and Cyclones
NCERT Solutions for Class 7th Science Chapter 7 : Winds, Storms and Cyclones
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’s surface warm air rises up whereas cold air comes down.
(d) Air moves from a region of high pressure to a region of lowpressure.
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 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:
Two experiences are:
(i) Take mouthful of air and close the mouth tightly. Now, press the cheeks with the fingers. The air inside mouth put pressure on it.
(ii) Take a balloon and blew it. We observe that the balloon which was shrunk earlier got tighten due to air pressure.
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:
Holes are made in hanging banners and hoardings in order to tackle the air pressure. The air get passed through these holes made on the hoardings or banners and thus reduces the pressure of air on them. Therefore, the hoardings do not get blown away or torned due to air pressure.
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:
Planning required in advance to deal with the situation created by a cyclone are:
(i) Cyclone alert or Cyclone watch should be issued 48 hours in advance of any expected storm.
(ii) The message should be broadcasted every hour or half hour when a cyclone is nearer the coast.
(iii) Armies and Rescue forces should be kept on high alert at the sign of disaster.
(iv) Medical team should be always be prepared for providing the first aid.
(v) Arrangement of safe drinking water and food should be made in time.
(vi) Government should ready with rehabilitation plan.
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
Page No: 93
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.