Question

In the shown system, $m_1>m_2$. Thread QR is holding the system. If this thread is cut, then just after cutting.

• A. Acceleration of mass $m_1$ is zero and that of $m_2$ is directed upward
• B. Acceleration of mass $m_2$ is zero and that of $m_2$ is directed downward
• C. Acceleration of both the blocks will be same
• D. Acceleration of system is given by $\left(\frac{m_1-m_2}{m_1+m_2}\right)\text{kg}$ where k is a spring factor.

Answer 1

The correct option is A Acceleration of mass $m_1$ is zero and that of $m_2$ is directed upward

On cutting of string QR, the resultant force $m_1$ remains zero because its weight $m_1\text{g}$ is balance by the tension in the spring but on block $m_2$ a resultant upward force $(m_1-m_2)\text{g}$ is developed. Thus block $m_1$ will have no resultant acceleration whereas $m_2$ does have an upward acceleration given by $\frac{(m_1-m_2)\text{g}}{m_2}$.