FORCE AND PRESSURE | Class 8 Science Notes
By ConceptScroll Team · Published on 17 July 2026 · 4 min read
FORCE AND PRESSURE – this guide gives you a concise, exam-ready overview of FORCE AND PRESSURE from Class 8 Science, written by ConceptScroll editors and reviewed against the latest NCERT textbook.
Pressure in Liquids
Liquids exert pressure on the walls of the container and on any object immersed in them. This pressure is due to the weight of the liquid above the point where pressure is measured. The pressure exerted by a liquid at a given depth depends on the density of the liquid, the acceleration due to gravity, and the depth below the surface.
The pressure at a depth h in a liquid of density ρ is given by the formula:
Pressure = ρ × g × h
where ρ (rho) is the density of the liquid (in kg/m³), g is acceleration due to gravity (≈ 9.8 m/s²), and h is the depth (in meters).
This pressure acts equally in all directions at a given depth. This is why liquids can exert pressure sideways and upwards as well as downwards.
An important consequence of this is that the pressure at the bottom of a container depends only on the height of the liquid column and not on the shape or volume of the container.
This principle is used in hydraulic machines, where a small force applied on a small piston produces a large force on a larger piston due to pressure transmission through the liquid.
Understanding pressure in liquids helps explain natural phenomena such as why dams are built with thick walls at the bottom and why submarines can withstand high pressure underwater.
In summary, pressure in liquids increases with depth and depends on the density of the liquid and gravitational acceleration. It acts equally in all directions and is fundamental to fluid mechanics.
📊 Diagram: Diagram showing a container filled with liquid, indicating depth h, and arrows showing pressure acting equally in all directions at that depth. Another diagram illustrates a hydraulic lift with small and large pistons connected by liquid.
🧪 Activity: Activity: Measuring pressure at different depths in a water column using a pressure sensor or observing water flow from holes at different heights in a container.
🔗 Connection: This section connects to the next section on atmospheric pressure and its effects.
Frequently asked questions
1. Give two examples each of situations in which you push or pull to change the state of motion of objects.
Examples of pushing to change state of motion: (i) Pushing a swing to make it move, (ii) Pushing a door to open it. Examples of pulling to change state of motion: (i) Pulling a drawer to open it, (ii) Pulling a rope in tug of war.
2. Give two examples of situations in which applied force causes a change in the shape of an object.
Examples: (i) Squeezing a lemon to extract juice changes its shape, (ii) Pressing a sponge changes its shape.
3. Fill in the blanks in the following statements. (a) To draw water from a well we have to ______ at the rope. (b) A charged body ______ an uncharged body towards it. (c) To move a loaded trolley we have to ______ it. (d) The north pole of a magnet ______ the north pole of another magnet.
(a) pull (b) attracts (c) push or pull (d) repels
4. An archer stretches her bow while taking aim at the target. She then releases the arrow, which begins to move towards the target. Based on this information fill up the gaps in the following statements using the following terms. muscular, contact, non-contact, gravity, friction, shape, attraction (a) To stretch the bow, the archer applies a force that causes a change in its _______. (b) The force applied by the archer to stretch the bow is an example of _______ force. (c) The type of force responsible for a change in the state of motion of the arrow is an example of a _______ force. (d) While the arrow moves towards its target, the forces acting on it are due to _______ and that due to _______ of air.
(a) shape (b) muscular (c) contact (d) gravity, friction
Ready to ace this chapter?
Get the full FORCE AND PRESSURE chapter — interactive notes, diagrams, worked solutions, polls and a free practice quiz — in the ConceptScroll app.
Study smarter with ConceptScroll
Daily NCERT-aligned reels, AI doubt solving and chapter quizzes — all free.
Start learning freeContinue reading
- LIGHT | Class 8 Science Notes
Clear NCERT-aligned notes on LIGHT for Class 8 Science.
- LIGHT | Class 8 Science Notes
Clear NCERT-aligned notes on LIGHT for Class 8 Science.
- LIGHT | Class 8 Science Notes
Clear NCERT-aligned notes on LIGHT for Class 8 Science.