NCERT Solutions for Class 8 Science Chapter 6 - Pressure, Winds, Storms, and Cyclones

NCERT Solutions for Class 8 Chapter 6 Download PDF

Students can download the NCERT Solution for Class 8 Science Chapter 6 Pressure, Winds, Storms, and Cyclones pdf from the icon given below. These solutions are prepared in a very comprehensive and systematic way.

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NCERT Solutions for Class 8 Science Chapter 6 ( Exercise Questions with Answers)

Given below the detailed explanations of exercise questions, these solutions are prepared to help students understand key concepts and perform well for exams. Students can also download Science Class 8 Chapter 6 solutions PDF.

Keep the curiosity alive

Question 1: Choose the correct statement.

(i) Look at Fig. 6.21 carefully. Vessel R is filled with water. When pouring of water is stopped, the level of water will be ____________________.

(a) the highest in vessel P

(b) the highest in vessel Q

(c) the highest in vessel R

(d) equal in all three vessels

Answer:

When water is poured into vessel R, through the connection, it flows into P and Q. Once it stops pouring water, it will settle at the same level in all three vessels because water always tries to balance its water in connected containers. So, the water level is equal in all three vessels.

Hence, the correct answer is option (d).

Question 1: Choose the correct statement

(ii) A rubber sucker (M) is pressed on a flat smooth surface, and an identical sucker (N) is pressed on a rough surface:

(a) Both M and N will stick to their surfaces.

(b) Both M and N will not stick to their surfaces.

(c) M will stick, but N will not stick.

(d) M will not stick, but N will stick

Answer:

Sucker M sticks to the flat surface because the sucker forms an airtight seal, which creates a vacuum.

Sucker N does not stick to the rough surface because air leaks in, which prevents the formation of a vacuum.

Answer:

Question 1: Choose the correct statement

(iii) A water tank is placed on the roof of a building at a height ‘H’. To get water with more pressure on the ground floor, one has to

(a) increase the height ‘H’ at which the tank is placed.

(b) decrease the height ‘H’ at which the tank is placed.

(c) Replace the tank with another tank of the same height that can hold more water.

(d) Replace the tank with another tank of the same height that can hold less water.

Answer:

Pressure due to liquid depends on the height and density of the tank. So water pressure increases with the height of the tank, so to get more pressure, the tank should be placed at a greater height.

Hence, the correct answer is option (a).

Question 1: Choose the correct statement

(iv) Two vessels, A and B, contain water up to the same level as shown in Fig. 6.22. PA and PB are the pressures at the bottom of the vessels. FA and FB are the forces exerted by the water at the bottom of the vessels A and B.

(a) PA = PB , FA = FB

(b) PA = PB , FA < FB

(c) PA < PB , FA = FB

(d) PA > PBB , FA > FB

Answer:

The pressure at the bottom of the liquid column depends on the height of the liquid. From the given image, both vessels have water at the same level. So the pressure at the bottom is equal.

PA = PB

But if the base of vessel B is wider than it will experience more force.

FA < FB

Hence, the correct answer is option (b).

Question 2: State whether the following statements are True [T] or False [F].

(i) Air flows from a region of higher pressure to a region of lower pressure. [ ]

(ii) Liquids exert pressure only at the bottom of a container. [ ]

(iii) The weather is stormy at the eye of a cyclone. [ ]

(iv) During a thunderstorm, it is safer to be in a car. [ ]

Answer:

(i). True

Air always moves from high-pressure to low-pressure areas

(ii). False

Because liquid exerts pressure in all directions.

(iii). False

The stormy weather occurs around the eye, and the eye of the cyclone is calm.

(iv). True

Because the car acts like a Faraday cage, the metal car allows the electric charge to pass around the outside, keeping you safe inside.

Question 3: Fig. 6.23 a shows a boy lying horizontally, and Fig. 6.23 b shows the boy standing vertically on a loose sand bed. In which case does the boy sink more in the sand? Give reasons.

Answer:

We know that

Pressure = Force/ Area

When the boy is standing vertically, as shown in the figure. 6.23(a) his weight is concentrated over a smaller area, which increases the pressure on the sand. As the area of contact with the sand is small, the pressure is high, causing the boy to sink more.

When the boy is lying on the ground, as shown in the figure. 6.23 (b) his weight spreads over a large area, resulting in less pressure and less sinking.

Hence, the boy sank more into the sand when he was standing vertically on the sand.

Question 4: An elephant stands on four feet. If the area covered by one foot is 0.25 m2, calculate the pressure exerted by the elephant on the ground if its weight is 20000 N.

Answer:

Given

Weight of the elephant = 20,000N

Area of the foot = 0.25m2

Number of feet =4

Total area in contact with the ground = Number of feet x Area of 1 foot

= 4 x 0.25 = 1m2

We know that

Pressure = Force / Area

= 20,000/1

=20,000 N/m2

Hence, the pressure exerted by the elephant on the ground is 20,000 N/m2

Question 5: There are two boats, A and B. Boat A has a base area of 7 m2, and 5 persons are seated in it. Boat B has a base area of 3.5 m2, and 3 persons are seated in it. If each person has a weight of 700 N, find out which boat will experience more pressure on its base and by how much?

Answer:

Given

Boat A

Base area = 7 m2

No of persons seated = 5

Weight of 1 person = 700 N

Total weight = 5 x 700 = 3500N

Boat B

Base area = 3.5 m2

No of persons seated = 3

Weight of 1 person = 700 N

Total weight = 3x700 = 2100 N

We know that

Pressure = Force / Area

Pressure on Boat A = Total weight on Boat A/ Base area

=3500/7

=500 N/m2

Pressure on Boat B = Total weight on Boat B/ Base area

= 2100/3.5

= 600 N/m2

Boat B will experience more pressure

Pressure difference = Pressure on Boat B - Pressure on Boat A

= 600 - 500

= 100 N/m2

Boat B will experience 100 N/m2 more pressure than Boat A

Question 6: Would lightning occur if air and clouds were good conductors of electricity? Give reasons for your answer.

Answer:

No, lightning would not occur if air and cloud both were good conductors of electricity.

Lightning occurs because air is a poor conductor of electricity, and it does not let electricity pass easily, thus causing electric charge to build up in the clouds. When too much charge builds up, it suddenly jumps through the air as lightning.

If both air and cloud were good conductors of electricity, the charge would move easily, and no lightning would form.

Question 7: What will happen to the two identical balloons A and B as shown in Fig. 6.24 when water is filled into the bottle up to a certain height? Will both the balloons bulge? If yes, will they bulge equally? Explain your answer.

Answer:

When water is poured into the bottle, it pushes the air inside the bottle downward and out through the side tube connected to the two balloons, which causes them to bulge. As the setup is symmetrical and both balloons are identical, air pressure is distributed equally.

Hence, both balloons will bulge equally due to equal amounts of air pressure acting on them.

Question 8: Explain how a storm becomes a cyclone.

Answer:

A storm becomes a cyclone when it grows in strength due to warm, moist air rising from the ocean surface. As the warm air rises, it creates the low-pressure area below. Air from surrounding areas with higher pressure rushes into the low pressure zone, this incoming air also gets warm and rises creating a cycle. As the process continues, the system begins to rotate due to earth rotation also known as coriolis effect. If the pressure continues and collects enough energy, the storm becomes stronger and develops into a cyclone.

Question 9: Fig. 6.25 shows trees along the sea coast on a summer afternoon. Identify which side is land A or B. Explain your answer.

Answer:

The trees in the image are bending from right to left, which shows the wing is directing from B to A.

On a summer afternoon the land heats up faster than the sea. The warm air above the land rises creating a low pressure area. Cooler air from the sea moves to replace it forming a sea breeze that flows from sea to land. From the given figure trees are bending towards A showing wind is blowing from B to A.

Hence, A is land and B is sea.

Question 10: Describe an activity to show that air flows from a region of high pressure to a region of low pressure.

Answer:

Take an empty plastic bottle and place a deflated balloon inside it.

Stretch the mouth of the balloon over the opening of the bottle.

Try to blow air into the balloon, you will find it difficult to inflate the balloon inside the bottle. This is because the bottle is already filled with air and the air inside the bottle creates pressure that opposes the air being blown into the balloon.

Now make a small hole at the bottom of the bottle and try to blow air into the balloon again. Now, the balloon inflates easily, because the air inside the bottle escapes from the hole which reduces the inside pressure.

Now the air from your mouth which is at higher pressure flows into the balloon which is at lower pressure.

This activity shows that air always flows from a region of higher pressure to a region of lower pressure.

Question 11: What is a thunderstorm? Explain the process of its formation.

Answer:

A thunderstorm is a weather condition that includes thunder, lightning, heavy rain and strong winds. It is caused by rapid upward movement of warm, moist air.

A thunderstorm forms when the ground heats up causing the warm, moist air to rise rapidly. As the air rises it cools and condenses to form clouds. This condensation releases heat making the air rise faster.

Inside the clouds strong air movement causes electric charge to build up leading to lightning and thunder. Then the condensed water falls as rain and the cool air rushes down with strong winds.
Question 12: Explain the process that causes lightning.

Answer:

Lightning is caused by building up and discharging electric charge in clouds.

During thunderstorms, strong air current moves upward while water droplets move downward inside the clouds. This movement causes positive and negative charges to separate where positive charge is collected at the top of the cloud and the negative charge collected at the bottom of the cloud. The ground below becomes positively charged due to this separation. When the difference between these charges becomes too large, the negative charge suddenly jumps on the ground or another cloud. This sudden flow of charge creates a big flash of light. And that is how lightning forms.

Question 13: Explain why holes are made in banners and hoardings.

Answer:

Holes are made in banners and hoardings to allow air to pass through them easily. Because when strong air flows it pushes against the surface of the banner. If there are no holes in the banner then the banner behaves like a solid wall which causes the banner to tear or fall down due to high air pressure. The presence of holes in banners and hoardings reduces air pressure by letting winds pass through, which helps to prevent damage and keeps the banner in place.

Approaches to Solve Chapter 6 Questions Effectively

To solve Class 8 Chapter 6 Science questions and answers effectively, it is important to follow a structured approach. Given below are the approaches to solve questions from this chapter:

1. Understand the Key Concepts

Before solving questions, it is very important to understand the basic concepts discussed in the textbook. Some important concepts are wind currents, air pressure, storms, cyclones, and thunderstorms.

2. Learn About the Concept of Pressure in Detail

The concept of pressure is a basic topic discussed in this chapter. Understand how air exerts pressure in all directions and how pressure changes with height and temperature.

3. Learn the process of formation of winds and cyclones

Pay special attention to how winds and cyclones formed, as questions from these topics are asked frequently in exams, and they also form the basis for other concepts as well. These concepts are explained well in NCERT Solution for Class 8 Science Chapter 6 Pressure, Winds, Storms, and Cyclones through a series of solved questions.

4. Study safety measures

Students must learn about precautions and safety steps to take during storms and cyclones. They help in both curriculum and real-life situations.

5. Practice questions

Practice questions from NCERT textbooks, as these questions are asked directly in exams. For revision students can follow NCERT notes for Class 7 Chapter 6.

NCERT Solutions for Class 8 Science Chapter 6: Topics

Given below the topics and subtopics discussed in Chapter 6. Students can use Science Class 8 Chapter 6 solutions PDF to understand the topics in detail.

6.1 Pressure

6.2 Pressure Exerted by Air

6.3 Formation of wind

6.4 High-Speed Winds Result in Lowering of Air Pressure

6.5 Storms, Thunderstorms, and Lightning

6.6 Cyclone

NCERT Chapter-Wise Solutions For Class 8 Science

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NCERT Solutions For Class 8 Subject-Wise

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NCERT Books and NCERT Syllabus

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