A : For a particle moving in a straight line, its acceleration must be either parallel or antiparallel to velocity.
R : A body moving along a curved path may have constant acceleration.

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 false statement, then mark (4).

Answer

To analyze the given statements, we need to evaluate both the assertion (A) and the reason (R) separately.

### Step 1: Evaluate Assertion (A)
The assertion states: "For a particle moving in a straight line, its acceleration must be either parallel or antiparallel to velocity."

- **Explanation**: When a particle moves in a straight line, its velocity vector points in a specific direction. For the particle to continue moving in a straight line, any change in its velocity (which is what acceleration does) must also occur in the same line. If the acceleration is parallel to the velocity, the particle speeds up; if it is antiparallel, the particle slows down. If the acceleration were to have a component perpendicular to the velocity, the particle would start to change direction, thus not moving in a straight line anymore.

### Conclusion for Step 1:
The assertion is **correct**.

### Step 2: Evaluate Reason (R)
The reason states: "A body moving along a curved path may have constant acceleration."

- **Explanation**: A body moving along a curved path can indeed have a constant acceleration. This is because acceleration is defined as the rate of change of velocity. Even if the speed (magnitude of velocity) remains constant, the direction of the velocity vector is continuously changing as the body moves along the curve. This change in direction constitutes acceleration, which can be constant in magnitude but varying in direction.

### Conclusion for Step 2:
The reason is also **correct**.

### Step 3: Relationship between A and R
Both the assertion and reason are correct, but the reason does not explain the assertion directly. The assertion discusses the nature of acceleration in straight-line motion, while the reason discusses the nature of acceleration in curved motion.

### Final Conclusion:
Both A and R are correct, but R does not explain A. Therefore, the correct answer is that both statements are true, but the reason is not a valid explanation for the assertion.

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