In a hydraulic system, if A1 = 3 square inches and F1 = 300 pounds, what is the pressure P?

• A. 60 psi
• B. 100 psi
• C. 300 psi
• D. 120 psi

Answer: (B)

Pressure is the force per unit area, so P = F / A. With a 300-pound force on an area of 3 square inches, the pressure is 300 ÷ 3 = 100 psi. This is the pressure the fluid carries and can be transmitted through the system to other parts, assuming ideal conditions with no losses. If you tried 60 psi, 300 psi, or 120 psi, you’d need different area or force values (for 60 psi you’d need 5 in²; for 300 psi you’d need 1 in² or 900 lb; for 120 psi you’d need 2.5 in² or 360 lb). Since the given values are fixed, the correct pressure is 100 psi.