Elastic and Inelastic Collisions - AP Physics C Mechanics

1. What is the formula for relative velocity in elastic collision?

   Initial relative velocity = - Final relative velocity. Speed of approach equals speed of separation.

2. What is the main characteristic of a perfectly elastic collision?

   Total kinetic energy is conserved. No kinetic energy is lost during collision.

3. What quantity is conserved in both elastic and inelastic collisions?

   Momentum. Always conserved when no external forces act.

4. What is true about the internal forces during a collision?

   Internal forces are equal and opposite. Newton's third law applies during collision.

5. What is the result of a perfectly inelastic collision on kinetic energy?

   Maximum kinetic energy is lost. Objects stick together, energy lost to deformation.

6. What do you assume about external forces when analyzing collisions?

   External forces are negligible. Collision duration is typically very short.

7. State the law of conservation of momentum.

   Total momentum before = Total momentum after. In isolated systems, momentum cannot be created or destroyed.

8. What is the significance of the coefficient of restitution?

   Measures elasticity of collisions. Ratio of separation to approach velocities.

9. Describe the velocity of separation in elastic collisions.

   Equal to initial velocity of approach. Coefficient of restitution equals one for elastic.

10. What is an elastic collision?

    Collision where kinetic energy is conserved. Both momentum and kinetic energy remain constant.

11. In a collision, how is energy dissipated?

    Converted to heat, sound, and deformation. Energy transforms from kinetic to other forms.

12. What does a zero coefficient of restitution indicate?

    Objects do not rebound after collision. Objects remain together after collision impact.

13. What is an inelastic collision?

    Collision where kinetic energy is not conserved. Momentum conserved but kinetic energy is lost to other forms.

14. How do you express the conservation of energy in elastic collisions?

    Initial KE = Final KE. Total kinetic energy remains constant throughout.

15. What is the coefficient of restitution for perfectly inelastic collisions?

    Coefficient = 0. Zero elasticity means maximum energy loss.

16. What is the coefficient of restitution for perfectly elastic collisions?

    Coefficient = 1. Maximum elasticity means no energy loss.

17. What is the effect of a collision on the system's center of mass?

    Center of mass velocity is unchanged. No external forces change system momentum.

18. Which collision type involves objects sticking together?

    Perfectly inelastic collision. Objects stick together after collision occurs.

19. In which type of collision is kinetic energy lost?

    Inelastic collision. Energy loss distinguishes inelastic from elastic collisions.

20. State the equation for kinetic energy.

    $KE = \frac{1}{2}mv^2$. Energy of motion depends on mass and velocity squared.

21. Identify the condition for total momentum conservation.

    No external forces on the system. Net external force must be zero for conservation.

22. What is impulse in the context of collisions?

    Change in momentum, $F \times t$. Force applied over time changes momentum.

23. What is the formula for momentum?

    $p = mv$. Mass times velocity gives linear momentum.

24. Identify the type of collision if kinetic energy is conserved.

    Elastic collision. No kinetic energy is lost to other forms.

25. What role does friction play in real-world collisions?

    Causes additional energy loss. Reduces kinetic energy through work done.

26. How is the conservation of momentum expressed mathematically?

    $m_1v_1 + m_2v_2 = m_1v_1' + m_2v_2'$. Vector form of momentum conservation law.

27. What determines the type of collision (elastic or inelastic)?

    Conservation of kinetic energy. Whether total kinetic energy remains constant.

28. In what type of collision does the coefficient of restitution equal zero?

    Perfectly inelastic collision. Objects stick together, no separation occurs.

29. What happens to kinetic energy in a completely inelastic collision?

    Partially lost to other forms. Energy converts to heat, sound, and deformation.

30. What happens to velocities in a perfectly inelastic collision?

    Objects stick together, shared velocity. Maximum energy loss occurs when objects combine.

31. What changes in a perfectly inelastic collision?

    Objects combine, single shared velocity. Objects stick together with common final velocity.

32. What is the kinetic energy formula for two colliding bodies?

    $\frac{1}{2}m_1v_1^2 + \frac{1}{2}m_2v_2^2$. Total kinetic energy before collision.

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