The block is placed on a frictionless surface in a gravity-free space. A heavy string of a mass $m$ is connected and force $F$ is applied on the string, then the tension at the middle of the rope is

Two masses of $10 \mathrm{kg}$ and $5 \mathrm{kg}$ are suspended from a rigid support as shown in the figure. The system is pulled down with a force of $150 \mathrm{N}$ attached to the lower mass. The string attached to the support breaks and the system accelerates downwards.


In case the force continues to act,  the tension acting between the two masses is

Two masses $m_1$ and $m_2$ are attached to a string which passes over a frictionless smooth pulley. When $m_1=6 \mathrm{kg},\mathrm{ }{m}_2=10 \mathrm{kg}$ the acceleration of masses is___ ($g=10\mathrm{ }\mathrm{m} {\mathrm{s}}^{-2}$)