Assertion : A shell at rest, explodes. The centre of mass of fragments moves along a straight path.
Reason : In explosion the linear momentum of the system remains always conserved.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If assertion is false but reason is true

Explanation

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

### Step 1: Understand the Assertion
The assertion states: "A shell at rest explodes. The center of mass of fragments moves along a straight path."

- When a shell explodes, it breaks into multiple fragments. Since the shell was initially at rest, the center of mass of the system (the shell and its fragments) should also remain at rest after the explosion, assuming no external forces act on it. Therefore, the assertion is **false** because the center of mass does not move along a straight path; it remains at rest.

### Step 2: Understand the Reason
The reason states: "In an explosion, the linear momentum of the system remains always conserved."

- According to the law of conservation of momentum, if no external forces act on a system, the total linear momentum of that system remains constant. Since the explosion is an internal process (the forces involved are internal), the total momentum before and after the explosion remains the same. Thus, the reason is **true**.

### Step 3: Conclusion
- Since the assertion is false and the reason is true, we conclude that the correct answer to the question is: **Assertion is false, Reason is true**.

### Final Answer
The correct answer is: **Assertion is false, Reason is true**.

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