Longitudinal strain is the fractional change in length of an object when a deforming force is applied along its length. It is a measure of how much an object stretches or compresses relative to its

It is calculated as the ratio of the change in length ($\Delta L$) to the original length ($L_0$):

$$\epsilon = \frac{\Delta L}{L_0}$$

Where:

• $\epsilon$ (epsilon) represents the longitudinal strain.
• $\Delta L$ is the change in length (final length - original length).
• $L_0$ is the original length of the object.

Since it is a ratio of two lengths, longitudinal strain is a dimensionless quantity and therefore has no units.