Question

Two blocks $A$ and $B$ of masses $2m$ and $m$, respectively are connected by a massless and inextensible string. The whole system is syspended by a massless spring as shown in the figure. The magnitude of acceleration of $A$ and $B$ immediately after the string is cut, are respectively:

• A. $g,\frac{g}{2}$
• B. $\frac{g}{2},g$
• C. $g,g$
• D. $\frac{g}{2},\frac{g}{2}$

Answer 1

Answer: (B)

Two blocks A and B of mass $2m$and $m$ respectively and they are connected by a mass less and in extensible string.

The equilibrium condition FBD of $2m$

$Kx=T+2mg$

$=mg+2mg=3mg$

After the string is cut

$T=0$

FBD of $2m$

$a_2=\frac{3mg-2mg}{2m}=\frac{g}{2}$

FBD of $m$

Hence $\frac{g}{2}$ and $g$