What it does
Push a drawing pin in with your thumb and it goes in easily, yet the same push from your palm leaves no mark. The difference is pressure: how much force lands on each square metre. This page presses two objects into pretend soft clay with the same force. A needle point puts it all on a tiny spot and slides in; a flat palm spreads it out and hardly marks the clay.
It shows the pressure under each object, how many times bigger one is, and the sum P = F ÷ A with your numbers. A graph plots pressure against area, so you can see that halving the area doubles the pressure.
It follows Class 8 Science, pressure, winds, storms and cyclones (force on an area, the pascal, sharp and broad objects), and at Class 11 thrust and pressure in powers of ten. Next, liquid pressure shows pressure growing with depth in water, and barometer altitude shows air pressure falling as you climb.
How to use it
- Choose the left and right objects, from a needle point to a snowshoe. Pick Your own area on the left for any area from 0.01 mm² to 1 m².
- Set the force with the slider, or drag up and down on the picture. Both objects get the same force.
- Read the pressures. The colour shows whether the clay hardly marks, dents, or the object goes in.
- Switch Level to Class 11 for powers of ten and to make the force come from a resting mass (weight = mass × 9.8 m/s², the thrust).
- Try Check yourself at the bottom.
Worked example
A needle point (0.01 mm² = 0.00000001 m²) and a flat palm (100 cm² = 0.01 m²) are each pressed with 100 N.
- Needle: P = 100 ÷ 0.00000001 = 10 GPa. It goes in.
- Palm: P = 100 ÷ 0.01 = 10 kPa. A dent only.
The needle gives 1,000,000 times more pressure, because its area is a million times smaller. A 2 kg brick (thrust 19.6 N) lying flat on 200 cm² presses with 980 Pa; on its end (50 cm²) it presses with 3,920 Pa.
FAQ
Is a pascal big or small? Small: one newton on a whole square metre. That is why kPa and MPa are common.
What is the difference between thrust and pressure? Thrust is the total force on a surface, in newtons. Pressure is that force shared over the area, in pascals.
Are the clay limits real? No. They are made-up values to show the idea.
Is anything stored? No. Everything runs in your browser.
Where the numbers come from
- Pressure = force ÷ area (thrust per unit area), 1 Pa = 1 N/m², weight = mass × g with g = 9.8 m/s² (rounded): standard school physics found in any textbook.
- The contact areas of the objects (needle point 0.01 mm², nail tip 1 mm², knife edge 10 mm², fingertip 1 cm², palm 100 cm², shoe 250 cm², snowshoe 0.1 m², a 20 × 10 × 5 cm brick) and the limits of the soft clay (dents above 5 kPa, gives way above 500 kPa) are made-up, rounded teaching values.
- The numbers were checked by hand and by an independent calculation in the tests (force ÷ area for every object, unit changes from cm² and mm² to m²).
Standard scientific values, such as constants, atomic weights and melting points, are facts found in every textbook; we name where ours were checked. If you are an author or publisher and want a value, a credit or a table changed or removed, tell us and we will act quickly.
Last updated 2026-11-10.