Question

A spring of spring constant 5 x 10${}^3$Nm${}^{-1}$ is stretched initially by $5cm$ from the unstretched position. Then the work required to stretch it further by another $5cm$ is

• A. $6.25Nm$
• B. $12.50Nm$
• C. $18.75Nm$
• D. $25.00Nm$

Answer 1

The correct option is C $18.75Nm$

Work done $=\frac{1}{2}k(x{{}_2}^2-x{{}_1}^2)$
$=\frac{1}{2}\times 5\times {10}^3\left(\right(10{)}^2-\left(5{)}^2\right)$
$=\frac{1}{2}\times 5\times {10}^3\frac{\left(75\right)}{10000}$
$=18.75$ N-m