These are not the same dimension. Pounds force is a unit of force. PSI means pounds per square inch, which is a unit of pressure (force per unit area).
The word gage refers to the fact that a pressure gage measures the difference between the pressure on the inside of a container and the outside. Normal atmospheric pressure is about 14 psi, so if a container of compressed air (like the tires on your car) measures 10 psi with a gage, the absolute pressure inside the tire is 14 + 10 = 24 pounds per square inch.
The total force acting on a square inch of the tire material is 24 pounds - 10 pounds from the inside, and 14 pounds from the outside. Note, I approximated the 14 psi atmospheric. The actual at sea level is "14.something", I just couldn't remember the exact amount
"Psi" says the formula. The pound per square inch or, more accurately, pound-force per square inch - symbol: psi or lbf/in2 or lbf/in2 - is a unit of pressure or of stress based on avoirdupois units. It is the pressure resulting from a force of one pound-force applied to an area of one square inch. 1 pound per square inch = 6 894.75729 pascals Pascal (Pa) is the SI unit of pressure.
You need to multiply by 0.036. So 5 x 0.036=.18 psi
To calculate the force generated by the piston, you can use the formula: Force = Pressure × Area. Given that the pressure is 100 psi and the area is 18 square inches, the force is 100 psi × 18 in² = 1,800 pounds. Therefore, a force of 1,800 pounds is generated when 100 psi is applied to the piston.
PSI stands for pounds per square inch. MPH stands for miles per hour. psi is used to measure pressure, and mph is used to measure speed. They have no relationship and cannot be converted to one another.
One psi (pounds per square inch) is 27.7 inches of water. An inch of water is a unit of pressure which will raise water one inch. A cubic inch of water weighs 0.0361 pounds, so one psi is one over 0.0361 or 27.7 inches of water.