1. Momentum

2. Momentum (ρ)
Energy in motion; product of an objects mass and its velocity.
Ρ = m•∆v
Mass and velocity are directly proportional.
To have a large momentum, an object will have a large mass, velocity, or both.
Objects at rest have no momentum.

3. Impulse (∆ρ)
Impulse is a force applied against a bodys motion for a given period of time.
∆ρ = Ft; Remember F = ma = m • ∆ v∕t
A force is needed to change a body’s momentum.
An unbalanced force is always accelerates an body.
If it acts in the direction of motion, then the body speeds up.
If it acts in the direction opposite of the motion, then the body slows down.

4. Collisions Impulse-momentum equation: F•t = m•∆v
In a collision, objects experience an Impulse; This impulse is equal and opposite to the change in momentum of a body.
Elastic and Inelastic Collisions
A perfectly elastic collision is defined as one in which there is no loss of kinetic energy in the collision. Conservation of momentum and conservation of kinetic energy are observed.
An inelastic collision is one in which part of the kinetic energy is changed to some other form of energy in the collision.
Three major facts about impulse and collision:
The impulse experienced by an object is the force • time.
The momentum change of an object is its mass • velocity.
Impulse equals change in velocity.

5. Law of Conservation of Momentum
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.
System: a collection of two or more objects.
Isolated system: a system that is free from the influence of a net EXTERNAL force that alters the momentum of the system.
Forces acting between two objects are equal and opposite in magnitude.
This is Newton’s Third Law of Motion.
The forces act between the two objects for a given amount of time.
Net external force:
Originates from a source other than the two objects of the system.
Is not balanced by other forces.