Define pressure and give its SI unit. Explain, with one example each, how pressure is increased and how it is reduced in daily life.

1. 1 · Define. Pressure is the thrust (perpendicular force) acting on unit area: P = F/A.
2. 2 · Give the unit. The SI unit is N m⁻², called the pascal (Pa).
3. 3 · Explain the rule. For the same force, a smaller area gives more pressure and a larger area gives less.
4. 4 · Example of more pressure. A sharp knife has a very thin edge, so a small push gives a large pressure and it cuts easily.
5. 5 · Example of less pressure. An army tank runs on wide chain belts, which spread its weight so it does not sink.
6. 6 · Close. So we change the area to get the pressure we need.

Scoring tip: Always write P = F/A with the unit pascal. Give one example of each kind.