Question

a steel plate measures '3 x 5'. If the pressure is 30lb/in2, calculate the force on the plate.

Answer 1

Given: $x = 3~\text{ft};~y = 5~\text{ft};~p = 30~\frac{\text{lb}}{\text{in}^2}.$

Since, by definition, pressure $p = \frac{F}{A},$ where F is force and A is area, and area of a rectangular plate is $A = xy,$ solving for the force, we get:

$F = pA = pxy.$

Entering the numerical values and converting the feet to inches (for canceling them out),

$F = 30~\frac{\text{lb}}{\text{in}^2}~*~(3*12)~\text{in}~*~(5*12)~\text{in} = 64800~lb,$

expressed in the pound-force units.