Momentum: the quantity of motion of a moving body, measured as a product of its mass and velocity.

Conservation of momentum: A conservation law stating that the total linear momentum of a closed system remains constant through time, regardless of other possible changes within the system.

Momentum Formula: momentum = mass x velocity or p = mv

Why P?

Newton thought of "moments" in a more mathematical, abstract sense in the calculus he was inventing (moments of inertia, for example). In the scientific community at the time Newton published the Principia, *impetus* was the quality of an object that was moving independent of an observed force. Furthermore, the equation p=m/v wasn't given first by Newton, but was developed afterwards. Many scientist/mathematicians developed what we now call "Newtonian Mechanics," and it's easy to imagine some sticking with the old impetus while others used the new momentum. P was a convenient symbol -- m would be confused with mass, i is too often used to indicate an instance of an object. (Mi usually means the mass of the object.)

Can a heavy moving van have the same momentum as a small motorcycle?


If a thing gets bigger, like a snowball rolling down a hill, then it gains more momentum. If a thing gets smaller (so it has less mass), then it has to spin faster, so that it has the same total momentum.

A sticky collision is one in which no kinetic energy is lost.         VS.

A non-sticky collision is one in which some of the kinetic energy of the colliding bodies is lost. This is because the energy is converted into another type of energy like heat or sound.

If you throw a piece of clay on the ground it would be a inelastic collision because when the clay slams into the ground, some of the kinetic energy of the clay was lost as heat and sound to the ground and air, and some of the heat remains in the clay. Since the velocity became zero, so did the momentum. The energy is still around, but divided up in different places.


the quantity of rotation of a body, which is the product of its moment of inertia and its angular velocity.

Kepler's law of equal areas states that the area swept out by a planet in a certain length of time is always the same. Angular momentum had not been invented in Kepler's time, and he did not even know the most basic physical facts about the forces at work. He thought of this law as an entirely empirical and unexpectedly simple way of summarizing his data, a rule that succeeded in describing and predicting how the planets sped up and slowed down in their elliptical paths. It is now fairly simple, however, to show that the equal area law amounts to a statement that the planet's angular momentum stays constant.But wait, why should it remain constant? --- the planet is not a closed system, since it is being acted on by the sun's gravitational force.it is actually the total angular momentum of the sun plus the planet that is conserved. The sun, however, is millions of times more massive than the typical planet, so it accelerates very little in response to the planet's gravitational force. It is thus a good approximation to say that the sun doesn't move at all, so that no angular momentum is transferred between it and the planet.