Q: Given a scientific passage and an answer, generate a question for the given answer.
Passage: When an action and reaction occur, momentum is transferred from one object to the other. However, the combined momentum of the objects remains the same. In other words, momentum is conserved. This is the law of conservation of momentum . Answer: momentum
A:
When an action and reaction occur, what is transferred from one object to the other, yet in combination it remains the same?