In the strain formula e = d/L, what does d represent?

• A. Original length
• B. Total elongation
• C. Strain
• D. Elastic modulus

Answer: (B)

The main idea is that strain is a ratio of how much something lengthens (or shortens) to its original length. In e = d/L, the d in the numerator is the actual change in length caused by the load—the total elongation. In other words, how much longer (ΔL) the piece becomes from its original length L. The strain e then expresses that change as a fraction of the original length.

So the correct interpretation is that d is the total elongation, the amount by which the length changes. The original length is the L in the denominator, not d; the strain is e, not d; and elastic modulus is a material property, not a length change.