How is pressure defined?

• A. Measure of a force supplied over a specific area
• B. Amount of heat energy per mole
• C. Speed of a moving fluid
• D. Electrical potential per unit area

Answer: (A)

Pressure is the force acting perpendicular to a surface per unit area. It’s defined by P = F / A, with units of pascals (N/m^2). This means the same force on a smaller area produces higher pressure, while spreading the force over a larger area lowers it. For example, a heavy object resting on a small area concentrates its force and creates high pressure, whereas distributing that force over a larger patch reduces pressure. The other descriptions refer to different concepts: heat energy per mole relates to energy content per amount of substance, the speed of a moving fluid is velocity, and electrical potential per unit area isn’t how pressure is defined (electric fields relate to potential gradient over distance).