Question

A spring of force constant $800N{m}^{-1}$ 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

$8J$

Step 1: Given data

Force constant $k=800N{m}^{-1}$

Step 2: Find work done

The work done is given by,

$$\begin{gathered} W=(1/2)k(x_2^2–x_1^2) \\ W=(1/2)x800x(0.{15}^2–0.{05}^2) \\ W=(1/2)x800x(0.0225–0.0025) \\ W=400x0.02 \\ W=8N/m \\ W=8J \end{gathered}$$

Hence, option B is correct.