All objects which are moving have momentum. The greater the mass of an object or the greater its velocity, the more momentum it has. This video explains what is meant by the idea of momentum, and how the transfer of momentum from one object to another allows for interesting things to happen in a system.
Please note that this topic will only be examined in the higher tier papers.
mass, closed system, friction, force, velocity, momentum, conservation of momentum, collision, explosion, Principle of Conservation of Momentum