Question

Two blocks of $4\text{kg}$ and $6\text{kg}$ are attached by springs and they are hanging in vertical position. Lower spring breaks due to excessive force. Acceleration of $4\text{kg}$ block just after breaking will be (Take $g=10m/s^2$)

• A. $15{\text{m/s}}^2$
• B. $25{\text{m/s}}^2$
• C. $10{\text{m/s}}^2$
• D. $\text{Zero}$

Answer 1

The correct option is A $15{\text{m/s}}^2$


Consider the system is in equilibrium before the lower spring breaks.
$\therefore$ The force on spring 1 is $kx=10g$.
when the spring 2 breaks, from the FBD we get
$10g-4g=4a$
$\therefore a=\frac{10g-4g}{4}=\frac{3g}{2}{\text{m/s}}^2=15{\text{m/s}}^2$