P = F/A Formula – Pressure Practice
P = F/A — Pressure as force per unit area
Pressure is force divided by area: P = F/A. Rearrange to F = PA or A = F/P. SI unit is the pascal (1 Pa = 1 N/m²).
Guide — how to use this formula
- 1. Use newtons and metres squared for Pa.
- 2. P = F/A, or rearrange for F or A.
- 3. Standing pressure: F = mg, then P = F/A.
- 4. 1 kPa = 1000 Pa.
Derivation
Pressure measures how concentrated a force is on a surface:
- Definition:
P = \frac{F}{A} - Hydraulic link (same P):
\frac{F_1}{A_1} = \frac{F_2}{A_2}
Convert cm² → m² (÷ 10,000) before using pascals.
Examples
Example: 50 N on 2 m²
P = 25 Pa.
Example: find F
P = 200 Pa, A = 0.5 m² → F = 100 N.