Pressure — REET Level 2 Science Notes
This page covers pressure for REET Level 2 Science — its definition, the formula (P=F/A), the unit, and everyday examples — in exam-focused form. REET 2024 asked a numerical-ratio question on this topic, so formula-based practice gets extra emphasis here.
- 1 question in REET 2024
- Class 6-8 level content
- 6 min read
How REET actually asks this topic
REET 2024 asked a proportional-reasoning question on pressure — how pressure changes when force is halved and area is doubled. In other words, REET is testing here not just the definition, but the ability to apply the formula P = F/A to numerical situations. So this page also gives several worked examples with different ratios, to prepare you for any numerical variation.
What is pressure? Definition and formula
The force acting per unit area of a surface is called pressure. Its formula is — pressure (P) = force (F) / area (A). It is a scalar quantity, which means it has no direction, and its magnitude alone fully defines it.
The idea of pressure helps explain why the same force can have very different effects in different situations — for instance, walking barefoot on pebbles hurts, while walking in shoes is comfortable, because the shoe increases the contact area and so reduces the pressure.
The SI unit of pressure is the pascal (Pa), which equals newtons per square metre (N/m²). The same force produces more pressure over a small area and less pressure over a large area — which is exactly why area has just as direct an effect on pressure as force does.
To make sense of the formula P = F/A, it helps to remember two separate relationships: pressure is always directly proportional to force and inversely proportional to area. This means that if both force and area change at the same time, the total effect on pressure is found by multiplying the two changes together.
Factors that affect pressure
- Increasing force (area constant)
- Pressure increases — pressure is directly proportional to force
- Increasing area (force constant)
- Pressure decreases — pressure is inversely proportional to area
- Halving force and doubling area
- New pressure = (F/2)/(2A) = one-quarter of the original pressure (the REET 2024 pattern)
- Increasing both force and area in the same ratio
- Pressure doesn't change at all, because the ratio F/A stays the same
Everyday examples of pressure
| Example | Principle |
|---|---|
| Sharpening the edge of a knife or needle | Reducing area to increase pressure, so it can cut or pierce easily |
| A porter placing a round cloth pad on their head | Increasing area to reduce pressure, making the load more comfortable |
| A camel's broad feet in sand | Large area, low pressure, prevents sinking into the sand |
| A wide shoulder strap on a bag | Increasing area to reduce pressure and cut down on pain |
| A tractor's wide tyres in a field | Increasing area to reduce pressure, so the tyres don't sink into wet soil |
| A sharp nail's point digging into a wall | Reducing area to increase pressure, so the nail goes in easily even with a small force |
| Wearing snow-shoes on snow | Increasing area to reduce pressure, so a person doesn't sink into soft snow |
| Wide sleepers beneath railway tracks | Spreading a heavy carriage's weight over a large area to reduce the pressure on the ground |
Atmospheric pressure (an introduction)
Air has weight too, and it presses down on the Earth's surface — this is called atmospheric pressure. The pressure inside our body balances the outside atmospheric pressure, which is why we normally don't feel it.
Atmospheric pressure decreases as altitude increases, because the layer of air above gets thinner and thinner. That's why mountaineers on high peaks find it hard to breathe and need extra oxygen.
Solids, liquids and gases can all exert pressure, but the pressure of a liquid or gas acts equally in all directions, while the pressure of a solid acts only on the surface it rests on. This is also why pressure increases with depth underwater.
How to teach this to children
Classroom activity
Press the same pencil against your palm gently, first with its sharp end and then with its blunt end, so children directly feel that a smaller area produces more pressure for the same force. The same experiment can be shown with two different kinds of shoes (a sharp heel versus a wide sole) pressed into wet mud.
Teaching aids
Press two differently sized pieces of cardboard into sand with equal force to show that the smaller piece sinks deeper. Record the results on the board and connect them back to the formula P=F/A.
Common misconception
Students often think more force always means more pressure; make it clear that area matters just as much — force and area together determine pressure. Also clarify that pressure and force have different units (pascal versus newton).
Assessment idea
Ask students, 'why can a camel walk easily in the desert while a person sinks in?' — this checks their understanding of the relationship between area and pressure. A numerical example can also be used to check whether they can correctly calculate pressure when force or area changes.
Memory trick
To remember pressure = force/area, think — 'smaller area means more pressure' (an inverse relationship) and 'more force means more pressure' (a direct relationship). In a numerical question, always plug the changed force and changed area into separate parts of the formula and multiply — don't just estimate. To check quickly, always substitute the new force and new area directly into P=F/A.
REET 2024 question (with solution)
Question 128
A Force (F) is acting on an area (A), if the force is halved and area is doubled then how much will be the pressure to the initial pressure ?
- Aचार गुना
- Bएकचौथाई
- Cआधा
- Dदुगुना
Explanation
दाब P = F/A। नया दाब P′ = (F/2)/(2A) = F/(4A) = P/4। अतः दाब प्रारम्भिक दाब का एक-चौथाई हो जाएगा। बल घटने और क्षेत्रफल बढ़ने – दोनों से दाब घटता है, इसलिए 'आधा' उत्तर अधूरा है।
Practice questions
Question 1
The formula for pressure is
- Aदाब = बल × क्षेत्रफल
- Bदाब = बल / क्षेत्रफल
- Cदाब = क्षेत्रफल / बल
- Dदाब = बल + क्षेत्रफल
Explanation
Pressure is defined as the force acting per unit area, so pressure = force / area.
Question 2
The SI unit of pressure is
- Aन्यूटन
- Bपास्कल
- Cजूल
- Dवाट
Explanation
The SI unit of pressure is the pascal (Pa), equal to newtons per square metre (N/m²).
Question 3
If the force on a surface is doubled while the area remains the same, the pressure will
- Aआधा हो जाएगा
- Bदुगुना हो जाएगा
- Cवही रहेगा
- Dचार गुना हो जाएगा
Explanation
Pressure is directly proportional to force; if area stays the same and force doubles, pressure doubles too.
Question 4
If the force remains the same but the area is tripled, the pressure will
- Aतिगुना हो जाएगा
- Bएक-तिहाई हो जाएगा
- Cवही रहेगा
- Dनौ गुना हो जाएगा
Explanation
Pressure is inversely proportional to area; if area triples, pressure drops to one-third (P' = F/3A = P/3).
Question 5
If the force is tripled and the area is doubled, the new pressure will be how many times the original pressure?
- A3/2 गुना
- B2/3 गुना
- C6 गुना
- D1/6 गुना
Explanation
New pressure P' = (3F)/(2A) = (3/2) × (F/A) = 3/2 times the original pressure.
Question 6
The purpose of sharpening the edge of a knife is to
- Aक्षेत्रफल बढ़ाकर दाब घटाना
- Bक्षेत्रफल घटाकर दाब बढ़ाना
- Cबल घटाना
- Dवज़न कम करना
Explanation
A sharp edge makes the contact area very small, so the same force produces more pressure, and the object cuts easily.
Question 7
A porter places a round cloth pad on his head before lifting a load. The reason for this is to
- Aदाब बढ़ाना
- Bक्षेत्रफल बढ़ाकर दाब घटाना
- Cबल बढ़ाना
- Dभार कम करना
Explanation
The round cloth pad increases the contact area, which reduces the pressure on the head and makes carrying a load more comfortable.
Question 8
To help children understand the concept of pressure in a practical way, a teacher would choose which of the following as the most suitable activity?
- Aकेवल सूत्र बोर्ड पर लिखना
- Bनुकीले व कुंद सिरे से हल्के दबाव का अंतर हथेली पर अनुभव कराना
- Cकेवल पाठ्यपुस्तक पढ़ाना
- Dपरिभाषा रटवाना
Explanation
Letting children directly feel the difference in pressure from a sharp versus a blunt point on their palm helps them understand that the same force over a smaller area creates more pressure — something rote formulas alone don't make clear.
Question 9
The scientific reason camels have wide feet is that
- Aअधिक बल लगाना
- Bअधिक क्षेत्रफल से कम दाब, रेत में न धंसना
- Cतेज़ दौड़ने में सहायता
- Dशरीर का भार कम करना
Explanation
Wide feet increase the contact area, which lowers the pressure on the sand, keeping a camel from sinking in.
Question 10
The most common misconception students have about pressure in class is that
- Aअधिक बल का अर्थ हमेशा अधिक दाब है, क्षेत्रफल की भूमिका नज़रअंदाज़ होती है
- Bदाब का कोई मात्रक नहीं होता
- Cदाब केवल ठोस पर लगता है
- Dदाब व बल एक ही राशि हैं, नाम अलग है
Explanation
Students often overlook the role of area; the teacher should make clear that pressure depends on both force and area.
Frequently asked questions
What is the SI unit of pressure?+
The SI unit of pressure is the pascal (Pa), equal to newtons per square metre (N/m²), and it is a scalar quantity.
What is the difference between pressure and force?+
Force is a push or pull acting on an object, while pressure is that force acting per unit area (pressure = force/area); the two also have different units.
How does REET ask questions on pressure?+
Often as a numerical ratio — such as the effect on pressure when force or area changes, as asked in REET 2024 — so practising plugging values into the formula and solving is essential.
Why is a knife's edge kept sharp?+
Keeping the edge sharp makes the area very small, so the same force produces much more pressure, and the object is cut easily.
What is atmospheric pressure?+
The pressure exerted on the Earth's surface because of the weight of air is called atmospheric pressure, and it decreases as altitude increases.
Why does pressure decrease when area is increased?+
Because pressure is inversely proportional to area — when the same force is spread over a larger area, less force acts per unit area, so the pressure drops.
Does pressure have a direction?+
No, pressure is a scalar quantity — it has only magnitude, not direction; this is exactly how it differs from force, which is a vector quantity.
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Official Sources
Change Log
- 17 September 2026 — English page published — mirrors the fact-checked Hindi page, independently bilingual-accuracy checked