Assertion: In projectile motion, the acceleration is constant in both magnitude and direction but the velocity changes in both magnitude and direction.
Reason: When a force or accelration is acting in an oblique direction to the direction of velocity then both magnitude and direction of the velocity may be changed.

Options

A. If both assertion `&` Reason are True `&` the Reason is a corrrect explanation of the Asserion.
B. If both Assertion `&` Reason are True but Reason is not correct explanation of the Assertion.
C. If Assertion is Trie but the Reason is False.
D. If both Assertion `&` Reason are false

Answer

To solve the question, we need to analyze the assertion and reason provided in the context of projectile motion.

### Step-by-Step Solution:

1. **Understanding Projectile Motion**:
- Projectile motion refers to the motion of an object that is thrown into the air and is subject to the force of gravity. It follows a curved path called a trajectory.

2. **Assertion Analysis**:
- The assertion states: "In projectile motion, the acceleration is constant in both magnitude and direction but the velocity changes in both magnitude and direction."
- In projectile motion, the only acceleration acting on the object is due to gravity, which is constant at approximately \(9.81 \, \text{m/s}^2\) downward. Therefore, the assertion is **true**.

3. **Velocity in Projectile Motion**:
- The velocity of the projectile changes due to the gravitational acceleration acting on it. The vertical component of the velocity decreases as the projectile rises and increases as it falls, while the horizontal component remains constant (assuming no air resistance). Hence, the velocity changes in both magnitude and direction, confirming that the assertion is **true**.

4. **Reason Analysis**:
- The reason states: "When a force or acceleration is acting in an oblique direction to the direction of velocity, then both magnitude and direction of the velocity may be changed."
- In projectile motion, the gravitational force acts downward, which is indeed oblique to the initial velocity vector (which has both horizontal and vertical components). This oblique force changes the direction of the velocity vector and affects its magnitude as well. Therefore, the reason is also **true**.

5. **Conclusion**:
- Since both the assertion and the reason are true, and the reason correctly explains the assertion, we conclude that both the assertion and reason are correct.

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

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