A fire alarm usually detects smoke in case of fire. Where should such an alarm be placed in a room?
(a) Near the door
(b) On the floor
(c) On any wall
(d) On the ceiling
Four schematic diagrams are shown in Figure 8.1 to depict the direction of sea breeze. Which of them gives the correct direction?
Figure 8.2 shows a child blowing air with a straw near the opening of another straw which has its other end in a soft drink bottle. It was observed that the level of the soft drink in the straw rises up as soon as air is blown over its open end. Which one of the following best explains the reason for the rise in the level of the drink?
(a) Blowing of air decreases pressure over the opening of the straw.
(b) The straw of the soft drink bottle collapses when air is blown over its open end.
(c) Blowing of air warms up the air inside the straw.
(d) Blowing of air increases the pressure on the surface of soft drink in the bottle.
Following are precautions one must take in case a storm is accompanied by lightning.
(i) Do not take shelter under a tree.
(ii) Do not take shelter under an umbrella with a metallic end.
(iii) Do not take shelter in open garages, storage sheds, etc.
(iv) Do not take shelter in a bus in the open.
Which one of these is not correct?
Which of the following place is most likely to be affected by a cyclone?
A curtain is hanging at the entrance of a room. A long corridor runs at right angles to the door, that is parallel to the curtain. If a strong wind blows along the corridor, the curtain will
(a) get pushed inside the room.
(b) get pushed outside the room.
(c) get collected towards one end/swirled.
(d) remain unaffected.
Name the ocean which is mainly responsible to bring rain-bearing monsoon winds to Kerala coast in June every year?
Fill in the blanks.
(i) Air around us exerts __________ .
(ii) The moving air is called _________ .
(iii) The main cause of wind movement is uneven ___________ on the earth.
(iv) High speed wind can cause cyclone in regions of ___________ pressure.
State whether the following statements are True or False:
(i) If wind flows from land to the ocean, then it is daytime.
(ii) A very high-pressure system, with very high-speed wind surrounding it forms a cyclone.
(iii) The coastline of India is not vulnerable to cyclones.
(iv) Warm air is lighter than cool air.
To expel hot air out of the kitchen, ‘A’ has an exhaust fan fitted on the window of her kitchen and ‘B’ has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the exhaust fan will expel the hot air more effectively? Explain why?
A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothesline in the balcony. Towards which direction the clothes will be blown in the afternoon? Explain.
Figure 8.3 shows a diagrammatic representation of trees in the afternoon along a sea coast. State on which side is the sea; A or B? Give reasons for your choice.
A flag mounted on a flag post near the sea coast flutters in the direction of the sea. At what time of the day does this happen – at midnight or in the afternoon?
Match Column I with Column II. There can be more than one match.
|Column 1||Column 2|
|a) On heating air||i) Descends|
|b) On cooling air||ii) Expands|
Paheli kept an empty bottle made of plastic inside a refrigerator. After a few hours, when she opened the refrigerator she found the bottle had collapsed. Explain the possible reason.
When strong/high speed wind blows, an umbrella held upright at times gets upturned. Explain the reason.
Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce wind storm
The picture in Figure 8.4 shows a tree line along the sea coast on an island near the equator. As shown, the treetops are permanently bent in one direction. Are the trees bent towards the sea or away from it? Explain.
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