As shown in the figure, two masses of \(10~\text{kg}\) and \(20~\text{kg}\), respectively are connected by a massless spring. A force of \(200~\text{N}\) acts on the \(20~\text{kg}\) mass. At the instant shown, the \(10~\text{kg}\) mass has an acceleration of \(12~\text{m/s}^2\) towards the right. The acceleration of \(20~\text{kg}\) mass at this instant is:
          
1. \(12~\text{m/s}^2\)
2. \(4~\text{m/s}^2\)
3. \(10~\text{m/s}^2\)
4. zero

What is the acceleration of block \(A\), if the acceleration of \(B\) is \(4~\text{m/s}^2\) towards the right at the instant shown?

                           
1. \(2.5~\text{m/s}^2\)
2. \(4~\text{m/s}^2\)
3. \(5~\text{m/s}^2\)
4. zero

Three blocks \(A\), \(B\) and \(C\) of mass \(3M\), \(2M\) and \(M\) respectively are suspended vertically with the help of springs \({PQ}\) and \({TU}\) and a string \({RS}\) as shown in Figure. The acceleration of blocks \(A\), \(B\) and \(C\) are \(a_{1} , a_{2}~ \text{and}~ a_{3}\) respectively.
                             

The value of acceleration \(a_{1}\) at the moment string \({RS}\) is cut will be: 
1. \(g\) downward
2. \(g\) upward
3. more than \(g\) downward
4. zero

Find the reading of the spring balance is shown in the figure.
(take \(g=10~\text{m/s}^2\) )
                

1. \(60~\text N\) 
2. \(40~\text N\)
3.  \(50~\text N\) 
4. \(80~\text N\)