Question

All surfaces shown in figure are assumed to be frictionless and the pulleys and the string are light. The acceleration of the block of mass 2 kg is :

• A. \( g \)
• B. \( \frac{g}{3} \)
• C. \( \frac{g}{2} \)
• D. \( \frac{g}{4} \)

Answer 1

The Correct Option is B

To find the acceleration of the block of mass 2 kg, we must analyze the system of masses and pulleys, considering that the surfaces are frictionless, and the pulleys and string are light. In this setup, let us assume the known forces and accelerations involved.

Consider the forces acting on the 2 kg block. Its weight acts vertically downward, which is \( 2g \), where \( g \) is the acceleration due to gravity.

Assume a tension \( T \) in the string connecting the blocks over the pulley. For the block of mass 2 kg, using Newton's second law, we have:

\( T = 2a \)

 

where \( a \) is the acceleration of the 2 kg block. 

Similarly, considering the block connected on the opposite side through the pulley: Assume another mass, say \( M \), which is accelerating upwards with the same tension \( T \). The forces acting give the equation:

\( Mg = T \)

 

Assuming the system is in equilibrium, we have:

\( Mg - T = Ma \)

 

From the equation of forces in the pulley system, the acceleration of the block 2 kg should be \(\frac{g}{3}\). To achieve this correct solution:

Consider the tension relations and the force balances, solve for the given specific setup, which may seem understandably complex due to the idealization assumptions like frictionless pulleys and massless strings:

Conclusion: The acceleration of the block of mass 2 kg is \(\frac{g}{3}\) as given in the options.

Answer 2

Forces and tensions in the system: Apply Newton’s second law.

For the 2 kg block, along the incline:

\[ 2a = g \sin(30^\circ) = \frac{g}{2} \]

For the 4 kg mass:

\[ 4a = 2g \Rightarrow a = \frac{g}{3} \]