Momentum In order to understand what is 'momentum', we might look at these 2 examples. 1. A charging elephant ( high mass, low speed) 2. A speeding bullet ( low mass, high speed) The difference between these two is written in the bracket. Two quantities that are considered to look at are MASS and SPEED (velocity). Now, let us think, which one is harder to stop? What is your answer?? Ok , the answer is BOTH. Is not it? You may think twice if you're still confused. Knowing that, the measure of HOW HARD TO STOP A MOVING OBJECT is called MOMENTUM. Momentum is the product between mass and velocity. The common symbol used for momentum is p. -----> p=mv Conservation of Linear Momentum A 'system' must has at least two moving objects moving in opposite directions. Remember that momentum is a vector quantity ( has direction). If the changes of momentum of the two objects are equal, they will cancel out as the directions are opposite. Hence, the over