A bar of length L, area A and Young's modulus E is subjected to a pulling force P. The strain energy stored in the bar is
- A. $PL²/AE$
- B. $PL²/2EI$
- C. $P^2L/2AE$
- D. $P^2L/AE$
Answer: C. $P^2L/2AE$
Explanation: Strain Energy $U = \frac{1}{2} P \delta = \frac{1}{2} P (PL/AE) = \frac{P^2L}{2AE}$.