Which expression correctly defines pressure in physics?

• A. Pressure equals force times area.
• B. Pressure equals area divided by force.
• C. Pressure equals force plus area.
• D. Pressure equals force divided by area.

Answer: (D)

Pressure is the force that is applied per unit area. This means how hard something pushes on a surface depends on both how much force there is and how spread out that force is over the area. The correct expression captures this idea: pressure equals force divided by area (P = F / A).

This shows why the same force over a larger area produces less pressure, while the same force over a smaller area produces more pressure. The units align as newtons per square meter, known as the pascal. For intuition: if you press with the same force over a bigger patch, you feel less bite or indention, and if you press with the same force on a tiny point, the pressure is much greater.

The other forms don’t describe pressure correctly: multiplying force by area would give a quantity with incorrect units; adding force and area mixes incompatible quantities; and dividing area by force would yield units that aren’t pressure (m^2/N).