Which equation correctly defines pressure in terms of force and area?

Which equation correctly defines pressure in terms of force and area?

• A. P = F*A
• B. P = F/A^2
• C. P = F/A
• D. P = F - A

Answer: (C)

Pressure is how concentrated a pushing force is on a surface. It’s defined as the force applied perpendicular to the surface divided by the area over which that force is spread. So the correct relationship is P = F / A. This means if you push with the same force over a larger area, the pressure drops, and if you push harder over the same area, the pressure rises. Units line up nicely: newtons per square meter, called a pascal. The other forms don’t match this idea. Multiplying force by area would give a quantity with the wrong units and interpretation. Dividing by area squared would give incorrect units and a different dependence on area. Subtracting area from force mixes incompatible quantities and isn’t a definition of pressure.

Pressure is how concentrated a pushing force is on a surface. It’s defined as the force applied perpendicular to the surface divided by the area over which that force is spread. So the correct relationship is P = F / A. This means if you push with the same force over a larger area, the pressure drops, and if you push harder over the same area, the pressure rises. Units line up nicely: newtons per square meter, called a pascal.

The other forms don’t match this idea. Multiplying force by area would give a quantity with the wrong units and interpretation. Dividing by area squared would give incorrect units and a different dependence on area. Subtracting area from force mixes incompatible quantities and isn’t a definition of pressure.