The video introduces momentum as a property of moving objects, defined as 'mass and motion'. It is mathematically expressed as p = m * v, where p is momentum (kg•m/s), m is mass (kg), and v is velocity (m/s). An object at rest has zero momentum.

A sample problem demonstrates how to calculate momentum: a 22 kg grocery cart moving at 1.2 m/s has a momentum of 26.4 kg•m/s. The example emphasizes that objects not moving have zero momentum.

Impulse is defined as the change in momentum. Changes in an object's velocity or mass result in a change in its momentum, hence an impulse. A force is required to change a body's momentum, and this force multiplied by the time of contact is equal to impulse. The formula given is Impulse = Force * Time = Change in (Mass * Velocity). The standard unit for momentum and impulse is Newton-second or kilogram-meter per second.

A problem demonstrates calculating the average force exerted on a football. Given the mass (0.42 kg), velocity (25.0 m/s), and contact time (0.050 s), the force is calculated as (mass * velocity) / time, resulting in 210 N (Newtons).

The video explains that impact force is directly proportional to momentum and inversely proportional to the time of contact. Increasing the time of contact decreases the impact force, as exemplified by airbags in cars, which reduce injury by extending the time of collision.

The lesson moves on to scenarios involving collisions, such as playing billiards. It highlights that during a collision, masses remain constant, but velocities and, consequently, momentum change. A change in momentum signifies the presence of impulse. An object experiencing a greater change in momentum also has a greater impulse.

Another scenario involving two colliding cars with equal mass but different initial velocities illustrates that the car with greater initial velocity experiences a greater change in velocity, a greater change in momentum, and thus greater impulse after the collision.