Pressure Formula
The pressure formula P = F/A calculates the force per unit area.
Understand pressure in pascals with practical worked examples.
The Formula
Pressure is the amount of force applied per unit area. The same force spread over a smaller area creates higher pressure.
Variables
| Symbol | Meaning |
|---|---|
| P | Pressure (measured in pascals, Pa, where 1 Pa = 1 N/m²) |
| F | Force applied perpendicular to the surface (measured in newtons, N) |
| A | Area over which the force is distributed (measured in square meters, m²) |
Example 1
A 600 N force is applied to a surface area of 0.03 m². What is the pressure?
Identify the values: F = 600 N, A = 0.03 m²
Apply the formula: P = F / A = 600 / 0.03
P = 20,000 Pa (or 20 kPa)
Example 2
A 70 kg person stands on one foot. The sole of the shoe has an area of 0.015 m². What pressure do they exert on the ground?
First find the force (weight): F = mg = 70 × 9.81 = 686.7 N
Apply: P = F / A = 686.7 / 0.015
P ≈ 45,780 Pa (approximately 45.8 kPa)
When to Use It
Use the pressure formula whenever force is distributed over an area.
- Calculating pressure exerted by objects on surfaces
- Hydraulic systems and fluid mechanics
- Understanding why sharp objects cut more easily (small area = high pressure)
- Tire pressure, atmospheric pressure, and engineering applications