The spring force is given by $F=-kx$ where $k$ is a constant and $x$ is the deformation of spring. Which of the following depicts $F-x$ graph ?

A constant force, $F=\frac{m_{1}g}{2}$ is applied on the block of mass $m_2$ as shown in figure. The string and the pulley are light and the surface of the table is smooth. Find the acceleration of $m_2$.

Two blocks $A$ and $B$ of masses $1.5 \mathrm{kg}$ and $0.5 \mathrm{kg}$ respectively are connected by a massless inextensible string passing over a frictionless pulley as shown in the figure. Block A is lifted until block B touches the ground and then block A is released. The initial height of block A is $80 \mathrm{cm}$ when block B just touches the ground. The maximum height reached by block $\mathrm{B}$ from the ground after the block A falls on the ground is

Mass $m$ shown in figure is in equilibrium. If it is displaced further by $x$ and released find its acceleration just after it is released. Take pulleys to be light and smooth and strings light.

A block of mass $m$ lies on wedge of mass $M,$ which lies on fixed horizontal surface. The wedge is free to move on the horizontal surface. A horizontal force of magnitude $F$ is applied on block as shown, neglecting friction at all surfaces, the value of force $F$ such that block has no relative motion w.r.t. wedge will be : (where $\mathrm{g}$ is acceleration due to gravity)