3. Impulse Newton’s second law of motion, F = ma, can be rewritten by using the definition of acceleration as the change in velocity divided by the time needed to make that change. It can be represented by the following equation

4. Multiplying both sides of the equation by the time interval, Δt, results in the following equation:

5. The right side of the equation, mΔv, involves the change in velocity: Δv = vf – vi.
Therefore, mΔv = mvf – mvi. The product of the object’s mass, m, and the object’s velocity, v, is defined as the momentum of the object.

6. Momentum is measured in kg•m/s
Momentum is measured in kg•m/s. An object’s momentum, also known as linear momentum, is represented by the following equation.

7. This will then give us the “Impulse Momentum Theory”
or… FΔt = Δp

12. Momentum in a Closed, Isolated System
Under what conditions is the momentum of the system of two balls conserved? The first and most obvious condition is that no balls are lost and no balls are gained. Such a system, which does not gain or lose mass, is said to be a closed system.
The second condition required to conserve the momentum of a system is that the forces involved are internal forces; that is, there are no forces acting on the system by objects outside of it.