Class 8 Science

Chapter 6 Solutions — Pressure, Winds, Storms, and Cyclones

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Solutions

Overview

Step-by-step NCERT solutions for Pressure, Winds, Storms, and Cyclones (Chapter 6, NCERT Class 8 Science) — every question and answer worked out in full, not just the final result. You can also read the Pressure, Winds, Storms, and Cyclones textbook chapter.

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What these solutions cover

All 13 questions in Pressure, Winds, Storms, and Cyclones are solved in the PDF. Here's what's inside, exercise by exercise:

Keep the Curiosity Alive

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
- (ii) A rubber sucker (M) is pressed on a flat smooth surface and an identical sucker (N) is pressed on a rough surface…
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) Weather is stormy at the eye of a cyclone.
- (iv) During a thunderstorm, it is safer to be in a car.
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 sand? Give reasons.
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.
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?
Would lightning occur if air and clouds were good conductors of electricity? Give reasons for your answer.
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.
Explain how a storm becomes a cyclone.
Fig. 6.25 shows trees along the sea coast in a summer afternoon. Identify which side is land — A or B. Explain your answer.
Describe an activity to show that air flows from a region of high pressure to a region of low pressure.
What is a thunderstorm? Explain the process of its formation.
Explain the process that causes lightning.
Explain why holes are made in banners and hoardings.

Sample

Worked examples

3 questions from Pressure, Winds, Storms, and Cyclones, solved step by step.

Keep the Curiosity Alive

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.

Given:

Weight of elephant (Force) = 20000 N

Area of one foot = 0.25 m²

Number of feet = 4

Total area of contact = 4 × 0.25 = 1.0 m²

Pressure = Force / Area

Pressure = 20000 N / 1.0 m²

Pressure = 20000 Pa (or 20000 N/m²)

Answer: Pressure = 20000 N ÷ 1.0 m² = 20000 Pa (20000 N/m²).

Keep the Curiosity Alive

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?

Given:

Boat A: base area = 7 m², number of persons = 5

Boat B: base area = 3.5 m², number of persons = 3

Weight per person = 700 N

Total weight on Boat A = 5 × 700 = 3500 N

Pressure on Boat A = Force / Area = 3500 / 7 = 500 N/m²

Total weight on Boat B = 3 × 700 = 2100 N

Pressure on Boat B = Force / Area = 2100 / 3.5 = 600 N/m²

Comparing: 600 N/m² > 500 N/m²

Boat B experiences more pressure by 600 − 500 = 100 N/m².

Answer: Boat B experiences more pressure (600 N/m²) than Boat A (500 N/m²) by 100 N/m².

Keep the Curiosity Alive

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

No, lightning would NOT occur if air and clouds were good conductors of electricity.

Reason: Lightning occurs because of a large build-up of electric charge in clouds — positive charges accumulate near the top of the cloud and negative charges near the bottom. Between the cloud and the ground (or between clouds), there is an insulating layer of air that prevents immediate discharge.

When the charge difference (potential difference) becomes very large, it overcomes the insulating resistance of air, causing a sudden massive discharge — this is lightning.

If air and clouds were good conductors, charge would flow continuously and smoothly without accumulating. There would be no build-up of a large potential difference, and therefore no sudden massive discharge. Lightning is essentially the result of charge being unable to flow gradually — it is forced to discharge explosively when the insulating barrier (air) is finally overcome.

Answer: No. Lightning requires a large build-up of charge in clouds. If air and clouds were good conductors, charge would flow continuously rather than accumulate, so no large potential difference would develop and no sudden lightning discharge would occur.

All 13 questions in Pressure, Winds, Storms, and Cyclones are solved step by step in the Solutions PDF above.

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Chapter 6 Solutions — Pressure, Winds, Storms, and Cyclones

Overview

What these solutions cover

Keep the Curiosity Alive

Worked examples

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.

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?

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

More solutions in Curiosity

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