When a weight is applied to a spring,it stretches by an amount $x$. What is the energy stored in it? ($T$ is the tension force developed in the spring and $k$ is the spring constant.)

The length of a spring is $l$ and its force constant is $k$. When a weight $W$ is suspended from it,its length increases by $x$. If the spring is cut into two equal parts and put in parallel and the same weight $W$ is suspended from them,then the extension will be

$A$ block of $3 \; kg$ is initially in equilibrium and is hanging by two identical springs $A$ and $B$ as shown in the figure. If spring $A$ is cut from the lower point at $t = 0$,find the acceleration of the block in $m/s^2$ at $t = 0$.

The length of a spring is $\alpha$ when a force of $4\,N$ is applied on it and the length is $\beta$ when $5\,N$ force is applied. Then the length of the spring when $9\,N$ force is applied is

Two blocks of mass $2 \, kg$ and $4 \, kg$ are accelerated with the same acceleration by a force of $10 \, N$ as shown in the figure on a smooth horizontal surface. Then the spring force between the two blocks will be .......... $N$ (the spring is massless).

Two masses of $1 \, kg$ and $2 \, kg$ respectively are connected by a massless spring as shown in the figure. $A$ force of $20 \, N$ acts on the $2 \, kg$ mass. At the instant when the $1 \, kg$ mass has an acceleration of $10 \, m/s^2$ towards the right,the acceleration of the $2 \, kg$ mass is ......... $m/s^2$.