Assertion: A projectile gets exploded at its highest point. All the piece get only horizontal velocities.
Reason: The weight of the projectile is the external force for projectile.

Options

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

Explanation

To analyze the given assertion and reason, we will break down the statements step by step.

### Step 1: Understand the Assertion
The assertion states: "A projectile gets exploded at its highest point. All the pieces get only horizontal velocities."
- At the highest point of a projectile's trajectory, the vertical component of its velocity (Vy) is indeed zero. However, this does not mean that when it explodes, all pieces will only have horizontal velocities. The pieces can have different velocities in various directions depending on the nature of the explosion.

### Step 2: Evaluate the Assertion
- Since the assertion claims that all pieces get only horizontal velocities, this is incorrect. The pieces can have vertical components of velocity as well, depending on how they explode. Therefore, the assertion is **false**.

### Step 3: Understand the Reason
The reason states: "The weight of the projectile is the external force for the projectile."
- The weight of the projectile (mg, where m is mass and g is acceleration due to gravity) acts downward throughout the projectile's motion. This force is indeed an external force acting on the projectile.

### Step 4: Evaluate the Reason
- The reason is correct because the weight of the projectile is the external force that affects its motion.

### Conclusion
- The assertion is **false**, and the reason is **true**. Therefore, the correct option is that the assertion is false while the reason is true.

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

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