A : If net force acting-on a system is zero, then work done on the system may be nonzero.
R : Internal forces acting on a system can increase its kinetic energy.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1).
B. If both Assertion & Reason are true but the reason is not the correct explanation of the assertion, then mark (2).
C. If Assertion is true statement but Reason is false, then mark (3).
D. If both Assertion and Reason are falsė statements, then mark (4).

Answer

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided in the statement.

### Step 1: Understand the Assertion (A)
The assertion states: "If the net force acting on a system is zero, then the work done on the system may be non-zero."

- **Explanation**: The net force being zero means that the external forces acting on the system balance each other out. However, this does not imply that no work can be done on the system. For example, if internal forces are acting within the system, they can still do work, leading to changes in the kinetic energy of the system.

### Step 2: Understand the Reason (R)
The reason states: "Internal forces acting on a system can increase its kinetic energy."

- **Explanation**: Internal forces are the forces that the particles of a system exert on each other. In certain cases, such as in an explosion, these internal forces can lead to a redistribution of energy within the system, resulting in an increase in the kinetic energy of the particles even when the net external force is zero.

### Step 3: Analyze the Relationship Between A and R
Now we need to determine if the reason correctly explains the assertion.

- Since internal forces can indeed lead to changes in kinetic energy, this supports the assertion that even if the net external force is zero, work can still be done on the system through internal interactions.

### Conclusion
Both the assertion (A) and the reason (R) are true, and the reason provides a correct explanation for the assertion.

### Final Answer
Both assertion and reason are true, and the reason is the correct explanation of the assertion.

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