Question

A block of mass $250g$ is kept on a vertical spring of spring constant $100N/m$ fixed from below. The spring is now compressed to have a length $10cm$ shorter than its natural length and the system is released from this position. How high does the block rise? ($g=10m/s^2$)

• A. $10cm$
• B. $30cm$
• C. $20cm$
• D. $40cm$

Answer 1

The correct option is C $20cm$

The given data is

$m=250g=0.250kg$

$k=100N/mx=10cm=0.1m$

$g=10m/se{c}^2$

Applying law of conservation of energy

$\frac{1}{2}k{x}^2=mgh$

$h=\frac{1}{2}\left(\frac{k{x}^2}{mg}\right)$

$h=\frac{1}{2}\left(\frac{100\times (0.1{)}^2}{2\times 0.25\times 10}\right)$

$h=0.2m$

$h=20cm$