Elasticity

This last expression of Young's modulus is perhaps the most valuable.

Since the numerator of the equation has the units of force divided by area, and the denominator is dimensionless, Y will have units of pounds per square inch (psi) in the FPS system.

If you know the material from which a structure is made and the load that is to be applied, you can find the deflection or change in length due to the load by using a different form of the equation, as shown above:

• Young's Modulus (Y) =

• or, by substituting the equations for stress and strain:

• which, after algebraic manipulation appears as:

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