Question

A force of $10N$ holds an ideal spring with a $20N/m$ spring constant in compression, The potential energy stored in the spring is :

• A. $0.5J$
• B. $2.5J$
• C. $5J$
• D. $10J$

Answer 1

The correct option is B $2.5J$

Solution

REF.Image

At Equilibrium

$F=KX$

$X=\frac{F}{K}=\frac{10}{20}=\frac{1}{2}$

We know,

Spring Energy = $\frac{K}{2}{X}^2=\frac{K}{2}(\frac{F}{K}{)}^2=\frac{1}{2}(\frac{F^2}{K})$

$\Rightarrow PE=\frac{1}{2}\left(\frac{10\times 10}{20}\right)=2.5J$

Option - B is correct.