What is meant by 'momentum is conserved'? - AQA - GCSE Physics - Question 5 - 2020 - Paper 1

Momentum is conserved when the total momentum of a closed system remains constant over time, regardless of the interactions occurring within the system. This means that the momentum before an event, such as a collision, is equal to the momentum after the event. This principle is fundamental in physics and applies to all interactions, implying that the total momentum is neither gained nor lost.