Q. 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 (given that string does not break)Physics Question Image

Work, Energy and Power Report Error

Solution:

Applying work-energy theorem on the block, we get
$F l-\frac{1}{2} k l^{2}=0$
$l=\frac{2 F}{k}$ or work done $=F l=\frac{2 F^{2}}{k}$
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