NCERT Solutions for Class 8th Science Chapter 6 Pressure, Winds, Storms, and Cyclones
Updated on 2026-09-19
About this chapter
Pressure is force per unit area , P = F/A . The same weight pressing on a smaller area gives a larger pressure — which is why a broad strap is comfortable, a pointed nail drives easily and a sharp knife cuts. The SI unit is N/m 2 , also called the pascal (Pa) . A liquid exerts pressure at the bottom of its vessel and on the walls — in fact in all directions . The pressure depends on the height of the liquid column , not on the width of the vessel or on the weight of liquid it holds. That is why overhead tanks are placed high and why a dam's base is broader than its top. Air also presses on everything around it. The pressure of the air surrounding us is the atmospheric pressure ; the force it exerts on just a 15 cm × 15 cm patch is about 2250 N — the weight of a 225 kg mass. We are not crus
- Chapter opener
- Chapter opening text · 6.1 Pressure
- .1 Pressure
- .2 Pressure Exerted by Air
- .2 Pressure Exerted by Air · 6.3 Formation of Wind
- .3 Formation of Wind
- .4 High-Speed Winds Result in Lowering of Air Pressure
- Chapter-end exercise, Questions 1–13
- Interdisciplinary projects
Quick revision
| Term | What it means | Where it comes in the chapter | Example from the book |
|---|---|---|---|
| Pressure | The force acting perpendicular to a surface, divided by the area of that surface: P = F/A | Section 6.1, pages 81–82 | A bag with broad straps presses less on the shoulders than one with narrow straps (Fig. 6.1) |
| Pascal (Pa) | The SI unit of pressure; 1 Pa = 1 N/m2 | Section 6.1, page 82 | 100 N on 2 m2 of cardboard gives 50 N/m2 = 50 Pa |
| Millibar (mb) / hectopascal (hPa) | Practical units of air pressure; 1 mb = 1 hPa = 100 Pa | A step further, page 87 | The isobars 994 mb, 996 mb, 998 mb, 1008 mb in Fig. 6.19 |
| Liquid pressure | Pressure exerted by a liquid column; it increases with the height of the column and acts in all directions | Activities 6.1 and 6.2, pages 83–85 | Equal water heights bulge both balloons equally (Fig. 6.5); water spurts from all four side holes (Fig. 6.7) |
| Atmosphere | The envelope of air surrounding the Earth — nitrogen, oxygen, argon, carbon dioxide and other gases in small quantities | Section 6.2, page 85 | It extends up to many kilometres above the Earth's surface |
| Atmospheric pressure | The pressure exerted by the air around us | Section 6.2, pages 86–87 | Air pushes a rubber sucker onto a smooth surface (Activity 6.4, Fig. 6.11) |
| Wind | Air in motion from a region of high pressure to a region of low pressure | Section 6.3, pages 87–89 | Air flows from the inflated balloon to the uninflated one through a straw (Activity 6.5, Fig. 6.12) |
| Sea breeze and land breeze | Daytime wind from sea to land, night-time wind from land to sea, caused by pressure differences over land and water | Section 6.3, pages 88–89 | Land heats faster by day, so the low pressure forms over the land |
| Storm | Strong winds accompanied by rain | Section 6.5, page 90 | Storms are frequent in hot, humid, tropical regions like India |
| Thunderstorm | A storm accompanied by lightning and thunder | Section 6.5, page 91 | Kalboishakhi in West Bengal, Bihar and Jharkhand; Bordoisila in Assam; mango showers in Kerala, Karnataka and Tamil Nadu |
| Lightning | The bright flash produced when a large build-up of charge breaks down the insulating property of air and charges suddenly flow | Section 6.5, page 91 | Within a cloud, between clouds, or between a cloud and the ground (Fig. 6.16) |
| Lightning conductor | A metallic rod fixed along a building's walls, pointed end above the highest point and other end buried deep in the ground | Ever heard of…, page 92 | It gives electric charges an easy path into the ground (Fig. 6.18) |
| Cyclone | A spinning system of clouds, winds and rain formed over warm ocean waters around a very low-pressure centre | Section 6.6, pages 92–93 | Cyclone Amphan (2020) had peak wind speeds of 270 km/h |
| Eye of the cyclone | The region of lowest pressure at the centre of a cyclone, where the wind is calm | Section 6.6, page 92 | The surrounding region has strong winds and heavy rainfall (Fig. 6.20) |
| Storm surge | The wall of ocean water, 3–12 m high, pushed towards the shore by cyclone winds | Section 6.6, page 93 | It floods coastal areas and areas far from the sea, and contaminates drinking water |
| IMD | The India Meteorological Department, which monitors cyclones and thunderstorms and issues alerts and warnings | Section 6.6, page 93 | Weather monitoring satellites let it track cyclones and predict their path |
Exercises
- Chapter opener — Probe and ponder Page 80
- Chapter opening text · 6.1 Pressure — In-text Questions Page 81
- .1 Pressure — In-text Questions Page 826
- .1 Pressure — Table 6.1: Record your observations Page 826
- .1 Pressure — In-text Questions Page 836
- .1 Pressure — Activity 6.1: Let us try and find out Page 836
- .1 Pressure — In-text Questions Page 846
- .1 Pressure — Activity 6.2: Let us find out Page 846
- .1 Pressure — In-text Questions Page 856
- .2 Pressure Exerted by Air — Activity 6.3: Let us explore Page 856
- .2 Pressure Exerted by Air — In-text Questions Page 866
- .2 Pressure Exerted by Air — Activity 6.4: Let us perform Page 876
- .2 Pressure Exerted by Air · 6.3 Formation of Wind — In-text Questions Page 876
- .3 Formation of Wind — In-text Questions Page 886
- .3 Formation of Wind — Activity 6.5: Let us observe Page 886
- .4 High-Speed Winds Result in Lowering of Air Pressure — In-text Questions Page 896
- .4 High-Speed Winds Result in Lowering of Air Pressure (Fig. 6.13) — Activity 6.6: Let us observe Page 896
- Chapter-end exercise, Questions 1–13 — Keep the curiosity alive Page 94
- Interdisciplinary projects — Discover, design, and debate Page 97