Assertion : Internal forces acting on the system cannot change linear momentum of the system .
Reason : Internal forces can change kinetic energy of the system.

Options

A. If both assertion and reason are corret and reason is a correct explanation of the assertion .
B. If both assertion and reason are correct but reason is ot the correct explanation of assertion .
C. If assertion is correct but reason is incorrect .
D. If both assertion and reason are incorrect .

Explanation

To solve the question, we need to analyze the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "Internal forces acting on the system cannot change the linear momentum of the system."

- **Explanation**: In an isolated system, the total external force acting on the system is zero. According to the law of conservation of momentum, if there are no external forces acting on a system, the total momentum of the system remains constant. Internal forces, which are forces that the objects in the system exert on each other, do not affect the total momentum of the system because they cancel each other out.

### Step 2: Understand the Reason
The reason states that "Internal forces can change the kinetic energy of the system."

- **Explanation**: While internal forces do not change the total momentum of the system, they can change the distribution of kinetic energy among the objects in the system. For example, if two objects collide, they exert internal forces on each other, which can change their individual speeds and thus their kinetic energies. However, the total kinetic energy may change depending on the nature of the interaction (elastic or inelastic collisions).

### Step 3: Evaluate the Relationship Between Assertion and Reason
Now we need to determine if the reason explains the assertion.

- The assertion is about the conservation of momentum, while the reason is about changes in kinetic energy. Although both statements are correct, the reason does not provide an explanation for the assertion. The assertion focuses on momentum conservation, while the reason discusses kinetic energy, which is a different concept.

### Conclusion
Based on the analysis:
- The assertion is true: Internal forces do not change the linear momentum of the system.
- The reason is also true: Internal forces can change the kinetic energy of the system.
- However, the reason does not explain the assertion.

Therefore, the correct option is that both the assertion and reason are correct, but the reason is not the correct explanation of the assertion.

### Final Answer
Both assertion and reason are correct, but the reason is not the correct explanation of the assertion.

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