Question

Initially the system shown in figure is in equilibrium. At the moment, the string is cut the downward acceleration of blocks $A$ and $B$ are respectively $a_{1}and{a}_2.$ The magnitudes of $a_{1}and{a}_2.$ are:

• A. zero and zero
• B. $2g$ and zero
• C. $g$ and zero
• D. None of the above

Answer 1

Answer: (B)

$2g$ and zero

spring force $=$ $m_{B}g$

Thus Tension acting in the string $=$ $m_{A}g+F_{spring}=(m_A+m_B)g$

after string is cut:

$a_A=g+F_{spring}/m_A=2g$ ($mA=mB$)

$a_B=g-F_{spring}/m_B=0$