Momentum = (mass)x(velocity)

p = (m)x(v) ... units are Ns

It is a vector in the same direction as velocity.

Connection to Newton's second law.

Q1, Q2.

A better football helmet

Momentum of Collisions and Newton's 3rd law.

Impulse is the total momentum change ... Impulse = (Force)x(time) and the area underneath a Force vs Time graph.

If we want to accomplish a change in momentum (generally related to changing velocity) then a large force for a short time will have the same affect as a small force for a long time. How would this look graphically?

Law of Conservation of Momentum: when no external forces act on the system, the total momentum of the system stays the same.

So pbefore = pafter (Q12 and Q13)

Collisions ...

Elastic: bodies separate and no energy is lost; momentum conserved.

Totally Inelastic: bodies stay together and large amounts of energy lost (thermal and sound); momentum conserved.

Inelastic: bodies separate but some energy is lost; momentum conserved.