Question:
A block of $2 \mathrm{~kg}$ is suspended from the ceiling through a mass less spring of spring constant $\mathrm{k}=100$ $\mathrm{N} / \mathrm{m}$. What is the elongation of the spring? If another $1 \mathrm{~kg}$ is added to the block, what would be the further elongation?
Solution:
$1^{\text {st }}$ Case:
mq=-kx
$x=\frac{-m g}{k}=\frac{-2 \times 9 .}{100}$
$=-0.196 m=-0.2 m$
2nd $^{\text {nd }}$ Case:
$m=3 k g$
$x^{\prime}=\frac{-3 \times 9.8}{100}=-0.294 m=-0.3 m$
$\left|x^{\prime}-x\right|=0.1 m$