$A$ block of mass $m$ is kept on a platform which starts from rest with constant acceleration $g/2$ upward,as shown in the figure. Work done by the normal reaction on the block in time $t$ is

$A$ block of mass $1 \, kg$ is suspended by a string of mass $1 \, kg$ and length $1 \, m$ as shown in the figure. Taking $g = 10 \, m/s^2$,calculate the force exerted by the support on the string. (in $, N$)

Three identical particles are joined together by a thread as shown in the figure. All the three particles are moving on a smooth horizontal plane about point $O$. If the speed of the outermost particle is $v_0$,then the ratio of tension in the three sections of the thread is:

$A$ body of mass $8\,kg$ is hanging from another body of mass $12\,kg$. The combination is being pulled upward by a string with an acceleration of $2.2\,m/s^2$. The tensions $T_1$ and $T_2$ will be respectively:

Two blocks of masses $7 \, kg$ and $5 \, kg$ are placed in contact with each other on a smooth surface. If a force of $6 \, N$ is applied on the heavier mass,the force on the lighter mass is ............ $N$.

Two masses $m_1$ and $m_2$ are placed on a smooth horizontal surface and are connected by a string of negligible mass. $A$ horizontal force $F$ is applied on the mass $m_2$ as shown in the figure. The tension in the string is