The question given below consist of an assertion and the reason . Use the following key to choose appropriate answer:
Assertion : There is a case of ground -to - ground projectile . When projectile is fired at an its path where instantaneous velocity becomes perpendicular to its initial velocity .
Reason : In case of ground -to- ground projectile projected at an angle `theta` , maximum possible deviation is `2 theta` ,

Options

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

Answer

To solve the problem, we need to analyze the assertion and the reason given in the question regarding projectile motion.

### Step 1: Understanding the Assertion
The assertion states that in a ground-to-ground projectile, there is a moment when the instantaneous velocity of the projectile becomes perpendicular to its initial velocity.

- When a projectile is launched at an angle θ with respect to the horizontal, it follows a parabolic trajectory.
- The initial velocity can be broken down into horizontal (Vx) and vertical (Vy) components.
- As the projectile moves, the vertical component of the velocity changes due to gravity, while the horizontal component remains constant.
- At the peak of the trajectory, the vertical component of the velocity becomes zero, and the projectile is momentarily moving horizontally.

**Conclusion for Step 1:** The assertion is true because there is indeed a moment when the instantaneous velocity (which is horizontal at the peak) is perpendicular to the initial velocity (which has both horizontal and vertical components).

### Step 2: Understanding the Reason
The reason states that for a ground-to-ground projectile projected at an angle θ, the maximum possible deviation is 2θ.

- The maximum deviation in the context of projectile motion refers to the total angle through which the projectile moves from its initial launch angle to the point where it lands.
- When a projectile is launched at an angle θ, it will land at an angle θ with respect to the horizontal on the opposite side of its launch point.
- Therefore, the total deviation from the initial direction to the landing direction is indeed 2θ.

**Conclusion for Step 2:** The reason is also true because the total deviation from the launch angle to the landing angle is 2θ.

### Final Conclusion
Both the assertion and the reason are true, and the reason correctly explains the assertion.