When an expolsive shell travelling in a parabolic path under the effect of gravity explodes in the mid air, the centre of mass of the fragments will move.

Options

A. a.vertically downwards
B. b.along the original parabolic path
C. c. vertically upwards and then vertically downwards
D. d. horizontallly followed by parabolic path

Explanation

To solve the problem, we need to analyze the situation of an explosive shell traveling in a parabolic path under the influence of gravity and what happens when it explodes.

### Step-by-Step Solution:

1. **Understanding the Initial Motion:**
- The shell is initially moving in a parabolic path due to the influence of gravity. This means that it has both horizontal and vertical components of velocity.

2. **Explosion of the Shell:**
- When the shell explodes, it breaks into fragments. This explosion is an internal event, meaning that the forces involved in the explosion act within the system of the shell and its fragments.

3. **Forces Acting on the System:**
- The only external force acting on the system is gravity. The explosion does not introduce any external forces; instead, it only redistributes the mass of the shell into fragments.

4. **Conservation of Momentum:**
- Since no external forces are acting on the system (other than gravity), the center of mass of the system must continue to move in the same manner as it was before the explosion. The momentum of the center of mass remains conserved.

5. **Path of the Center of Mass:**
- Because gravity continues to act on the fragments after the explosion, the center of mass of the fragments will continue to follow the same parabolic path that the shell was following before the explosion.

6. **Conclusion:**
- Therefore, the center of mass of the fragments will continue to move in a parabolic path, just like the original shell.

### Final Answer:
The center of mass of the fragments will move in the same parabolic path as the shell was moving before the explosion.

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