Select the false statement

Options

A. In elastic collision, KE is not conserved during the collision
B. The coefficient of restitutio for a collision between two steel balls lies between 0 and 1
C. The momentum of a ball colliding elastically with the floor is conserved
D. In an oblique elastic collision between two indentical bodies with one of them at rest initially, the final velocities are perpendicular

Answer

To solve the question of selecting the false statement regarding collisions, we will analyze each statement one by one.

### Step-by-Step Solution:

1. **Understanding Elastic and Inelastic Collisions**:
- In an elastic collision, both momentum and kinetic energy are conserved.
- In an inelastic collision, momentum is conserved, but kinetic energy is not conserved.

2. **Analyzing Statement A**:
- Statement A claims: "In an elastic collision, kinetic energy is conserved."
- This statement is true for elastic collisions. However, if it refers to inelastic collisions, it is false since kinetic energy is not conserved in inelastic collisions.

3. **Analyzing Statement B**:
- Statement B claims: "The coefficient of restitution for a collision between two steel balls lies between 0 and 1."
- This statement is true. The coefficient of restitution (e) is defined as the ratio of the relative velocity of separation to the relative velocity of approach, and it indeed lies between 0 (perfectly inelastic) and 1 (perfectly elastic).

4. **Analyzing Statement C**:
- Statement C claims: "In elastic collision, the momentum P is conserved."
- This statement is also true. Momentum is conserved in all types of collisions, including elastic collisions.

5. **Analyzing Statement D**:
- Statement D claims: "In an oblique elastic collision between two identical bodies with one of them at rest, the final velocities are perpendicular to each other."
- This statement is true. For two identical bodies colliding elastically, if one is at rest, the angles of deflection will indeed be complementary (sum to 90 degrees).

6. **Conclusion**:
- After analyzing all statements, we find that Statement A is misleading because it implies that kinetic energy is conserved in an inelastic collision, which is false. Therefore, the false statement is **Statement A**.

### Final Answer:
The false statement is **A**: "In an elastic collision, kinetic energy is conserved."

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