Pressure Defined as Force per Unit Area

Steps:

• Recall the standard definition of pressure in physics.
• Identify that pressure measures how force is distributed over a surface.
• Compare this to the given choices to match the exact wording.
• Confirm the unit of pressure (e.g., Pascals) aligns with force/area.

Why A is correct:

• Pressure is defined by the formula P = F/A, where P is pressure, F is force, and A is area, directly stating force per unit area.

Why the others are wrong:

• B: Force per unit volume describes something like stress in fluids, not pressure.
• C: Mass per unit area relates to surface density, not pressure.
• D: Mass per unit volume is density, unrelated to force or pressure.

Final answer: A