Chapter 8, Winds, Storms and Cyclones |
Class 7 |Science| NCERT Solutions
Question 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 1 (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 cooler air comes down.
(d) Air moves from a region of high pressure to a region of low pressure
Question 2. Suggest two methods to find out wind direction at a given place.
Answer 2 1) Take bits of paper on your palm. Allow them to fall from your hand.It will flow in the direction of wind flowing.
2)Fly a kite. The direction in which the kite flies will give you the wind direction.
Question 3. State two experiences that made you think that air exerts pressure (other than those given in the text).
Answer 3 1) It is difficult to ride a bicycle against the wind.
2) Balloons can be used only when they are filled with air.
Question 4. You want to buy a house. Would you like to buy a house having windows but no ventilators? Explain your answer.
Answer 4 A house without ventilators is not healthy to live in because there is no circulation of air in such house.Warm air is lighter and rises up and exit from ventilators whereas cool air is heavier and move in through window making the house comfortable ,fresh and healthy to live in.
Question 5. Explain why holes are made in hanging banners and hoardings.
Answer 5 Holes are made in hanging banners and hoardings in order to handle air pressure.As we know that air exert pressure, the holes allow the air to pass through them and thus reduces the pressure.So that hanging banners and hoarding do not become loose, fall down and tear.
Question 6. How will you help your neighbours in case cyclone approaches your village/town?
Answer 6 We can help our neighbours in case cyclone approaches us in following ways:
1) By giving rapid warnings to the government agencies and all other important places.
2) By shifting them, their important household goods, cattle and vehicles to safer places.
3) By storing water for safe drinking.
4) By providing first aid to the injured ones.
Question 7. What planning is required in advance to deal with the situation created by a cyclone?
Answer 7 Planning required in advance to deal with cyclone-hit situation are:
1) Moving to the safer place.
2) Store enough food in water proof bags.
3) Store safe drinking water.
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.
6) Rescue operation should be kept on high alert at the sign of disaster.
Question 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 8 (iii) Amritsar
Question 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 9 (i) In winter the winds flow from the land to the ocean.