# AQA A-Level Physics/Momentum

Momentum Concepts- Force as a rate of change of momentum. This links to Newton’s Second Law, which states that the rate of change of momentum of an object is directly proportional to the resultant force applied and is in the direction of the resultant force. The resultant force is equal to the rate of change of momentum.

Impulse: Impulse of a force is finding the product of the force acting on an object and the amount of time it’s having the force act upon it. Impulse is a vector quantity and its units are in kilogram metre per second, or Newton seconds. From this we can find that the impulse is the equal to the change in momentum of an object.

Area under a force-time graph: This area shows us the impulse of the force applied, which in turn tells us the change in momentum of the object. Principle of the conservation of momentum: The principle of the conservation of momentum when two objects interact the total momentum remains the same providing there are no external forces acting on the system.

Elastic and Inelastic Collisions: Elastic collisions are those in which the kinetic energy is conserved. You have the same total kinetic energy at the end as you do at the start. Inelastic collisions are when some energy is lost from the system and so the kinetic energy does not remain the same. Some of the kinetic energy will have been dissipated to the surroundings the form of other energies, such as heat or sound.