Momentum can be most commonly defined as “mass in motion”(Mom). Like many other mathematical and scientific ideas, it was not invented or created by one person. The first ideas of momentum came from Ren Descartes, a French philosopher, mathematician, and scientist. His ideas were furthered and developed by no one other than Sir Isaac Newton; Newton took ideas of his own and with help from Descartes formed the Laws of Motion (Wiki). The laws together contain the Law of Conservation of Momentum. The Law is as follows:
“For a collision occurring between object 1 and object 2 in an isolated system the total momentum of the two objects before the collision is equal to the total momentum of the two objects after the collision. That is, the momentum lost by object 1 is equal to the momentum gained by object 2” (Mom). The momentum of a group of objects that is conserved is constant and does not change.
The equation for momentum is P=MV which is momentum equals mass times velocity. For example, if I were to run at full speed into a wall, you would calculate my momentum by gathering my mass and multiplying that by my volume. A lot of real world connections to momentum can be tied mostly with sports like baseball. In baseball, for example when the pitcher throws the ball, it has momentum as soon as it leaves the pitches hand and changes its direction and amount of momentum when the ball is hit by that bat. The same for football, if the running back receives the ball in a play and begins to run he has a considerable amount of momentum and when he is tackled by the defense of the opposing team his momentum is gradually slowing down until it ultimately stops. A common misconception in conceptual physics is that an object needs to be going fast to have substantial momentum. On the contrary, large objects can collect large amounts of momentum even if its speed is very slow because it has a lot of mass. Imagine two instances where you find yourself crossing the street. In one example: you get hit by a sports car moving at 50 miles per hour with 40 pounds for its mass and in the other you get hit by a large moving truck moving at 40 miles per hour and with 50 pounds for mass. You will get hit harder with the momentum from the truck because it has more mass.
Momentum is otherwise known as a vector quantity. A vector quantity is “fully described by both magnitude and motion”(Mom). For example, it is not possible to full describe the motion of a kickball being tossed to a player. You need to add information about the direction and magnitude of the ball.
There are two types of momentum, regular and angular. Any object that is spinning will have angular momentum. Objects that collect velocity have linear momentum; in most common cases linear momentum will be referred to as just “momentum”.