Question: An elastic string of unstretched length 𝐿 and force constant 𝑘 is stretched by a small length 𝑥. It is further stretched by another small length 𝑦. The work done in the second stretching is
(A) \dfrac{1}{2}ky^{2}
(B) \dfrac{1}{2}k\left( x^{2}+y^{2}\right)
(C) \dfrac{1}{2}k\left( x+y\right) ^{2}
(D) \dfrac{1}{2}ky\left( 2x+y\right)
Answer: Option (D)
Solution:
