Short Answer
2v is the best answer.
This concept lives inside the mechanics toolkit: forces, motion, energy, momentum, and rotation. The safest way to solve it is to name the governing law first, then connect the variables in units you trust.
In the limit M≫m, the light ball bounces back at approximately 2v (twice the heavy ball's velocity).
Why This Answer Is Correct
This is a Hard-level question in Classical Mechanics. The prompt is really testing whether you can connect the concept to its defining physical relationship instead of picking a nearby-but-wrong term.
Mechanics questions usually become easier once you identify whether the problem is about force balance, kinematics, energy, or conservation.
Choices At A Glance
- A. v
- B. 2v
- C. 3v
- D. v/2
When similar options appear on an exam, eliminate the ones that break the core law, use the wrong units, or confuse a definition with a consequence.
Topic Snapshot
Topic: Classical Mechanics
Difficulty: Hard
Best next move: Re-state the governing law in your own words, then solve one more example from the same topic before moving on.