In a perfectly inelastic collision between two bodies

Options

A. There is maximum possible loss of energy .
B. Mechanical energy of the system remains constant .
C. Kinetic energy first decreases and then becomes constant .
D. Kinetic energy before collision is greater than kinetic energy after collision .

Explanation

To solve the problem regarding a perfectly inelastic collision between two bodies, we will analyze the key concepts and principles involved in such a collision.

### Step-by-Step Solution:

1. **Definition of Perfectly Inelastic Collision**:
In a perfectly inelastic collision, two bodies collide and stick together after the collision. The coefficient of restitution (e) for this type of collision is zero.

**Hint**: Remember that in a perfectly inelastic collision, the two bodies do not separate after colliding.

2. **Kinetic Energy Consideration**:
During the collision, kinetic energy is not conserved. Some of the kinetic energy is transformed into other forms of energy, such as heat or deformation energy. This means that the total kinetic energy after the collision is less than the total kinetic energy before the collision.

**Hint**: Think about what happens to the energy during a collision. Energy can be transformed but not created or destroyed.

3. **Mechanical Energy Conservation**:
The total mechanical energy of the system is not conserved in a perfectly inelastic collision. The kinetic energy lost is converted into heat or deformation energy, leading to a decrease in the total mechanical energy of the system.

**Hint**: Mechanical energy includes both kinetic and potential energy. In this case, focus on the kinetic energy aspect.

4. **Kinetic Energy Loss**:
The maximum possible loss of kinetic energy occurs during a perfectly inelastic collision. The kinetic energy before the collision is greater than the kinetic energy after the collision.

**Hint**: Compare the kinetic energy before and after the collision to see how much energy is lost.

5. **Final Kinetic Energy**:
After the collision, the kinetic energy reaches a minimum value and remains constant. This is because the two bodies move together as a single system post-collision.

**Hint**: Consider the motion of the combined mass after the collision to understand how kinetic energy behaves.

6. **Comparison of Initial and Final Kinetic Energy**:
The initial kinetic energy of the individual bodies before the collision is greater than the final kinetic energy of the combined mass after the collision. This confirms that energy has been lost.

**Hint**: Use the concept of conservation of momentum to relate the initial and final velocities of the combined mass.

### Summary of Correct Options:
- A: There is a maximum possible loss of energy (Correct)
- B: Total mechanical energy of the system remains constant (Incorrect)
- C: Kinetic energy first decreases then becomes constant (Correct)
- D: Kinetic energy before collision is greater than after collision (Correct)

### Final Answer:
The correct options are A, C, and D.