Question

A spring of force constant $800N/m$ has an extension of $5cm$. The work done in extending it from $5cm$ to $15cm$ is

• A. $16J$
• B. $8J$
• C. $32J$
• D. $24J$

Answer 1

The correct option is B $8J$

$Workdone,W=\frac{1}{2}k(x_2^2-x_1^2)$

$=\frac{1}{2}k\left[\right(0.15{)}^2-\left(0.05{)}^2\right]$

$=\frac{1}{2}\times 800\times 0.02=8J$