If you know the desired output force and the available supply pressure, which formula gives the necessary piston area?

• A. A = F / P
• B. A = F × P
• C. A = P / F
• D. A = F + P

Answer: (A)

In hydraulics, output force comes from pressure acting over an area, described by F = P × A. To find the piston area when you know the desired force and the available pressure, you solve for A by rearranging the equation: A = F / P. This makes sense dimensionally: force divided by pressure gives an area. For example, if you want 1000 N of force and have 200 kPa of pressure, the needed area is 1000 / 200,000 = 0.005 m² (which is 50 cm²). Using other forms wouldn’t produce an area with correct units: multiplying F by P mixes units, dividing P by F yields a 1/area unit, and adding F and P combines incompatible quantities. The division approach directly links the knowns to the piston area you need.