As shown in the figure, two masses of 10 kg and 20 kg, respectively are connected by a massless spring. A force of 200 N acts on the 20 kg mass. At the instant shown, the 10 kg mass has an acceleration of 12 m/s² towards the right. The acceleration of 20 kg mass at this instant is:
        
1. 12 m/s² 

2. 4 m/s² 

3. 10 m/s² 

4. Zero

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

                          
1. \(2.5~m/s^2\)
2. \(4~m/s^2\)
3. \(5~m/s^2\)
4. Zero

Two masses, A and B, each of mass M are fixed together by a massless spring. A force acts on the mass B as shown in the figure. If the mass B starts moving away from mass A with acceleration 'a' in the ground frame, then the acceleration of mass A will be:

Two blocks, A and B, of masses 2m and 4m are connected by a string. The block of mass 4m is connected by a spring (massless). The string is suddenly cut. The ratio of the magnitudes of accelerations of masses 2m and 4m at that instant will be:

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 fig. The acceleration of blocks A, B and C are $a_1,a_2 and a_3$ 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

A massless and inextensible string connects two blocks \(\mathrm{A}\) and \(\mathrm{B}\) of masses \(3m\) and \(m,\) respectively. The whole system is suspended by a massless spring, as shown in the figure. The magnitudes of acceleration of \(\mathrm{A}\) and \(\mathrm{B}\) immediately after the string is cut, are respectively:
         

Calculate the reading of the spring balance shown in the figure: (take \(g=10\) m/s²)
                

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

Three blocks each of mass m are hanged vertically with the help of inextensible strings and ideal springs. Initially, the system was in equilibrium. If at any instant, the lowermost string is cut, then the acceleration of block B just after cutting the string will be:

 The length of a spring is  \(l_1\) and \(l_2\) when stretched with a force of 4 N and 5 N respectively. Its natural length is?

If the system shown in the figure is in equilibrium, then the reading of spring balance (in kgf) is:

1. 10

2. 20

3. 100

4. Zero