Question

Initially spring is relaxed. A person starts pulling the spring by applying a variable force $F$. Find out the work done by $F$ to stretch it slowly to a distance by $x$.

• A. $\frac{K{x}^2}{1}$
• B. $\frac{K{x}^2}{2}$
• C. $\frac{K{x}^2}{4}$
• D. $\frac{K{x}^2}{8}$

Answer 1

Answer: (B)

$\frac{K{x}^2}{2}$

$\int dW=\int F.ds={\int }_0^{x}Kxdx\Rightarrow W={\left(\frac{k{x}^2}{2}\right)}_{\circ }^x=\frac{K{x}^2}{2}$