A block attached to a spring, pulled by a constant horizontal force, is kept on a smooth surface as shown in figure. Initially, the spring is in the natural length state. Then the maximum positive work that the applied force F can do is (give that string does not break)

Options

A. `(F^(2))/(K)`
B. `(2F^(2))/(K)`
C. `oo`
D. `(F^(2))/(2K)`

Answer

B

Explanation

`(B)` Applying work energy theorem on block.

`Fl-(1)/(2)kl^(2)=0:. l=(2F)/(k)`
work done `|=Fl=(2F^(2))/(k)`