Living Science 2020 2021 Solutions for Class 7 Science Chapter 15 Winds, Storms And Cyclones are provided here with simple step-by-step explanations. These solutions for Winds, Storms And Cyclones are extremely popular among Class 7 students for Science Winds, Storms And Cyclones Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Living Science 2020 2021 Book of Class 7 Science Chapter 15 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Living Science 2020 2021 Solutions. All Living Science 2020 2021 Solutions for class Class 7 Science are prepared by experts and are 100% accurate.
Page No 174:
Question 1:
Which is higher–the atmospheric pressure at Mumbai or the atmospheric pressure on top of Mt Everest? Give reasons.
Answer:
Atmospheric pressure at Mumbai would be higher. Because atmospheric pressure is higher at the surface of the earth and goes on decreasing as we move up into the earth's atmosphere. Mount Everest is a very high peak. That's why the pressure at the Mount Everest would be lower and pressure at the Mumbai would be higher.
Page No 174:
Question 2:
Fast wind can lift off a roof from a house. Does this happen because of increased pressure or reduced pressure?
Answer:
Fast wind can lift off a roof from a house because fast-moving wind reduces the pressure above the roof of a house and due to reduced air pressure from upside the downside air pushes it out and lift it off.
Page No 174:
Question 3:
A closed container has air at 20°C. Some air at 50°C is inserted into the centre of the container. In which direction will this air move–upwards, downwards or not all?
Answer:
The air with more temperature will be lighter and hence will rise in upwards direction to the top of the container.
Page No 178:
Question 1:
At the latitude of 20° N, in which direction do you normally expect winds to blow–towards the equator or away from the equator? What about 20° S? Give reasons.
Answer:
The area between 30° N and 30° S is an area of high pressure, from there the winds blow towards the equator and towards the poles. 20° N lies between the 30° N and equator, so at the latitude of 20° N, the winds blow towards the equator. Same happens at the 20° S, it lies between 30° S and equator. Hence, at the altitude of 20° S, the winds blow towards the equator.
Page No 178:
Question 2:
Thunder is produced by sudden heating of air. What is this heating due to?
Answer:
The heating is due to lightning. Lightning increases the pressure and temperature of the air, which produces thunder.
Page No 178:
Question 3:
The strongest winds in a cyclone occur in the centre on the 'eye' of storm. Do you agree? Give reasons.
Answer:
The 'eye' of the storm at the center is a calm and cloudless area. So, strongest winds do not occur at the center but at the edge of the cyclone.
Page No 178:
Question 4:
Where does a cyclone start–over land or over the sea?
Answer:
A cyclone is a violent storm, usually accompanied by strong winds and heavy rainfalls. It develops over the sea and then may move to some ground.
Page No 179:
Question 1:
Air exerts pressure in
(a) all directions.
(b) downward direction only.
(c) upward direction only.
(d) sideways only.
Answer:
(a) all directions
Air pressure is caused due to the constant bombardment of moving air molecules on the surface of the body. Hence, it exerts pressure in all directions.
Page No 179:
Question 2:
Low atmospheric pressrue exists on the earth in which of the following latitudes?
(a) at the equator only
(b) at 30° N and S
(c) at the Poles
(d) at the equator and at 60° N and S
Answer:
(d) at the equator and at 60o N and S
At equator, earth gets maximum heat from the sun. Thus, air gets warm and rises up creating a low pressure area. At 60o N and S, air is again warmer than the air at poles; therefore, it rises up and creates a low pressure area.
Page No 179:
Question 3:
Which of the following are not associated with cyclones?
(a) strong winds
(b) heavy rains
(c) tidal waves
(d) volcanic eruptions
Answer:
(d) volcanic eruptions
Volcanoes are not associated with cyclones.
Page No 179:
Question 4:
Development and movement of cyclones are studied by the
(a) Indian Postal Department
(b) Indian Forensic Department
(c) Indian Meteorological Department
(d) Central Investigation Department
Answer:
(c) Indian Meteorological Department
Development and movement of cyclones are studied by the Indian Meteorological Department.
Page No 179:
Question 5:
Which of the following states of India is most likely to be hit by a cyclone?
(a) Punjab
(b) Madhya Pradesh
(c) Andhra Pradesh
(d) Jammu and Kashmir
Answer:
(c) Andhra Pradesh
Andhra Pradesh is the state that is most likely to be hit by a cyclone.
Page No 180:
Question 6:
A piece of plywood is kept on a table. You have to lift it from the table by blowing air over it at very high speed from a powerful fan. In which direction will you blow air?
(a) in the upward direction
(b) in the downward direction
(c) sideways
(d) in the upward direction below the table
Answer:
(c) sideways
This will create a low pressure area above the plywood and it will be blown away by the wind coming to low pressure area.
Page No 180:
Question 7:
The fact that, increased wind speed results in reduced air pressure is known as
(a) Galileo principle
(b) Bernoulli principle
(c) Newton principle
(d) Einstein principle
Answer:
(b) Bernoulli principle
The fact that, increased wind speed results in reduced air pressure is known as Bernoulli principle.
Page No 180:
Question 8:
Which of these best describes a tornado?
(a) strong thunderstorm
(b) the eye of a cyclone
(c) rotating funnel of high speed with 10-15 km across
(d) rotating funnel of high speed with 10-200 m across
Answer:
A tornado is rotating funnel of high speed wind with 10-200 m across.
Page No 180:
Question 1:
Does air temperature increase of decrease as you go up in the atmosphere?
Answer:
Air temperature decreases as we go up in the atmosphere.
Page No 180:
Question 2:
Does air pressure increase of decrease as you go up in the atmoshpere?
Answer:
Air pressure decreases as we go up in the atmosphere.
Page No 180:
Question 3:
A rubber sucker pressed on a flat surface sticks to the surface because air pressure inside it is ____________ (more/less) than the air pressure outside.
Answer:
A rubber sucker pressed on a flat surface sticks to the surface because air pressure inside it is less than the air pressure outside.
Page No 180:
Question 4:
The faster the air moves, the ___________ (greater/smaller) is the pressure.
Answer:
The faster the air moves, the smaller is the pressure.
Page No 180:
Question 5:
When air expands, it rises up. True of false?
Answer:
True; when air expands, it rises up because on heating air expands, becomes lighter and rises up.
Page No 180:
Question 6:
Where is the air pressure higher-at the equator or at the Poles?
Answer:
Air pressure is high at the poles.
Page No 180:
Question 7:
Monsoon winds flow because of uneven heating of land and ___________
Answer:
Monsoon winds flow because of uneven heating of land and water.
Page No 180:
Question 8:
Lightning is an electric spark between clouds. True of false?
Answer:
It is true. Lightning is an electric spark between clouds.
Page No 180:
Question 9:
Calm conditions do not prevail anywhere in the cyclone. True of false?
Answer:
It is false that calm conditions do not prevail anywhere in the cyclone.
There is a calm and cloudless area at the centre of the storm called the eye.
Page No 180:
Question 10:
Cyclonic winds tend to circulate around the ___________ of the cyclone.
Answer:
Cyclonic winds tend to circulate around the eye of the cyclone.
Page No 180:
Question 1:
Name any four natural hazards.
Answer:
Four natural hazards are as follows:
1) earthquakes
2) floods
3) droughts
4) cyclones
Page No 180:
Question 2:
In which direction does air exert maximum pressure?
Answer:
Air exerts equal pressure in all directions.
Page No 180:
Question 3:
The speed of wind in a region suddenly increases. How does this affect the pressure in the region?
Answer:
The pressure in the region will decrease if the speed of the wind increases.
Page No 180:
Question 4:
Why does heated air rise up?
Answer:
On heating, air expands and becomes light. So, it rises up.
Page No 180:
Question 5:
What causes monsoon winds?
Answer:
The uneven heating of land and sea water causes monsoon winds. In summer, land becomes warmer than the sea. This causes winds to flow from sea to land and brings moisture with them. In winter, the direction of the wind gets reversed and there is hardly any moisture in it.
Page No 180:
Question 6:
What causes lightning during a thunderstorm?
Answer:
The water droplets and ice crystals in the upper regions of the atmosphere collide with each other due to swift rising of the air. These collisions produce static electricity and the clouds get charged. This results in huge sparking between the clouds or between the clouds and the ground. This is called lightning.
Page No 180:
Question 7:
Why does a cyclone become weak once it hits land?
Answer:
A cyclone becomes weak once it hits the land because of its friction with the land and shortage of moisture.
Page No 180:
Question 8:
What causes a tornado to be formed?
Answer:
Tornadoes are formed when a funnel-like column of cold air sinks down from a storm cloud. Warm air from the earth's surface rises up, whirls around and causes high speed winds.
Page No 180:
Question 1:
Explain why a rubber sucker pressed on a smooth surface gets stuck to the surface.
Answer:
A rubber sucker pressed on a smooth surface gets stuck to the surface because of air pressure. When pressed against a flat smooth surface like a wall, air is forced out between the sucker pad and the wall. This reduces the air pressure in the space between the sucker pad and the wall in comparison to the air pressure outside. Hence, greater air pressure outside the sucker pad firmly presses it to the wall.
Page No 180:
Question 2:
Describe an experiment to show that increased wind speed leads to reduced air pressure.
Answer:
Hold a strip of paper about 2 cm wide between the forefinger and the thumb of the hand and blow air over its top. Make sure that the fingers do not obstruct the flow of air over the paper strip. It is observed that instead of going down, the far end of the paper begins to lift upwards. The harder the air is blown, the higher it will lift. This happens because when air is blown over the paper, the air pressure above the paper reduces. The air pressure below the paper remains the same. As the pressure below is now greater than that above the paper, it pushes the paper above.
Page No 180:
Question 3:
(a) In which direction does wind blow between the equator and latitude 30°N? Why?
(b) Why does the wind swerve to one side instead of blowing straight?
Answer:
a) The wind between the equator and latitude 30°N blows from latitude 30o N towards the equator. As the regions close to the equator get maximum heat from the sun, the air near the earth's surface becomes warm and rises, producing a low pressure region. Cooler air from either side of the equator upto latitude 30o rushes in to occupy the vacant place.
b) The wind swerves to one side instead of blowing straight because of the rotation of the earth on its axis. The rotation causes the wind in the northern hemisphere to swerve to its right and the wind in the southern hemisphere to swerve to its left.
Page No 181:
Question 4:
What are the hazards associated with a cyclone?
Answer:
High speed winds of tropical cyclones are accompanied by heavy rains and huge sea waves. Flooding is caused by the huge waves as they hit the coast, and the accompanying rain further worsens the situation. Trees get uprooted, houses collapse, and telecommunication lines get disrupted. All these can lead to heavy loss of life and property.
Page No 181:
Question 5:
Describe the 'eye of a cyclone'.
Answer:
At the centre of the storm is a calm, cloudless area called the eye. It's diameter ranges from 10 km to 30 km. No rains are found here and the winds are fairly light. The strongest winds (normally 150-250 km/h) and heaviest rains are formed in the thick clouds around the eye.
Page No 181:
Question 6:
How is the forecasting of cyclones done in India?
Answer:
The Indian Meteorological Department studies the development and movement of cyclones. This is done with the help of the INSAT satellites and Chain Detection Radars (CDRs) installed along the coastal belt of India. These radars can locate and track an approaching cyclone within a range of 400 km.
Page No 181:
Question 7:
What precautions are needed in the cyclone-prone areas?
Answer:
Following precautions are needed in the cyclone prone areas:
(i) Listen weather bulletins on TV and radio regularly.
(ii) Keep an emergency kit ready at home.
(iii) Store enough food articles in waterproof bags.
(iv) Store safe drinking water as contaminated water can cause diseases.
(v) Keep the phone numbers of hospitals, government agencies like police, relatives and friends handy.
(vi) As soon as the warning is issued, secure your home well or move to safe places.
(vii) Do not venture into the sea.
(viii) After the cyclone, check gas leakages and dry all the electrical appliances.
(ix) Avoid flood water and be careful of snake bites.
Page No 181:
Question 8:
Draw a labelled diagram of the structure of a cyclone. Mark the direction of winds surrounding the eye.
Answer:
Page No 181:
Question 1:
You may have seen holes made in huge hoardings. Why are these necessary?
Answer:
The holes in huge hoardings are necessary to avoid any pressure difference between the two sides of the hoardings. In the absence of such holes, the pressure difference will tear the hoardings.
Page No 181:
Question 2:
News item in a newspaper: 'A cyclone, that started in the desert of Rajasthan, hits Delhi today.' Is the news item correct? Give reasons.
Answer:
Given news item is not correct because cyclones are formed only in warm, wet conditions usually over seas.
Page No 181:
Question 3:
In winter, in regions near the equator, why does wind blow from land to the sea?
Answer:
In winter, in regions near the equator, wind blows from land to the sea because in winter, the air pressure above the sea is less than the air pressure above land. So, wind from land comes to fill the low pressure area above the sea
Page No 181:
Question 4:
Suppose the earth rotated from east to west, instead of from west to east. How would this affect the pattern of wind circulation on the earth?
Answer:
If the earth starts rotating in opposite direction, the winds in the northern hemisphere will swerve to its left and the winds in the southern hemisphere will swerve to its right.
Page No 181:
Question 5:
The figure shows wind blowing at high speed in a narrow region. Will the pressure be high or low at A, B and C?
Answer:
The pressure at points B and C will be same and equal. However, the pressure at point A will be lower than that at points B and C.
Page No 181:
Question 1:
People get injured if a natural calamity such as a tornado strikes. They also get injured in accidents such as a road accident or a fire accident. Often you find people not ready to help the injured persons.
Suppose you see an injured person lying on the road after a road accident. What will you do?
Answer:
I will call an ambulance and will take him to the hospital.
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