Select the false statement

Options

A. Inelastic collision, kinetic energy during the collision is not conserved
B. The coeffficient of restitution for a collision between two steel balls lies between zero and one
C. The momentum of a ball colliding elastically with the floor is conserved
D. In an oblique elastic collision between two indentical bodies with initially one of them at rest, final velocities are perpendicular

Answer

To solve the problem 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. Some kinetic energy is transformed into other forms of energy, such as heat or sound.

**Hint:** Remember that inelastic collisions involve a loss of kinetic energy, while elastic collisions conserve both momentum and kinetic energy.

2. **Analyzing the First Statement:**
- The first option states: "In elastic collision, kinetic energy during the collision is not conserved."
- This statement is **false** because, in an elastic collision, kinetic energy is conserved.

**Hint:** Recall the definitions of elastic and inelastic collisions to determine the conservation of kinetic energy.

3. **Analyzing the Second Statement:**
- The second option states: "Coefficient of restitution of collision between two steel bars lies between 0 to 1."
- This statement is **true**. The coefficient of restitution (e) is defined to be between 0 (perfectly inelastic) and 1 (perfectly elastic).

**Hint:** The coefficient of restitution measures the elasticity of a collision and is always between 0 and 1.

4. **Analyzing the Third Statement:**
- The third option states: "The momentum of a ball colliding elastically with the floor is conserved."
- This statement is **false** in the context of the ball colliding with the floor because the floor exerts a force on the ball, changing its momentum during the collision.

**Hint:** Consider the external forces acting on the ball during the collision with the floor.

5. **Conclusion:**
- The false statements are the first and third options. However, since the question asks for one false statement, we can conclude that the first option is the most clearly false statement regarding elastic collisions.

### Final Answer:
The false statement is: "In elastic collision, kinetic energy during the collision is not conserved."