UT Homework is due Thursday the 26 th !!

 Defined as the product of a body’s mass and its velocity.  Vector quantity that points in the direction of the velocity.  SI unit is the kgm/s  A fast moving car will have more momentum than a slower car with the same mass.

This means that we exert force to Change an object’s momentum. (Duh!)

 In an isolated system of bodies, the momentum remains constant.  Generally, momentum is NOT conserved:  In the presence of friction (object loses KE because it gains thermal energy)  When the object is working against gravity (object loses KE because it gains PE)

 Recall :  This means that a force applied over time results in a change in momentum.  This is called Impulse! (J)

 Impulse (J) = area under the curve  ∆p = Impulse (J) = area under the curve  Area 1:.5x.02secx60N=.6kgxm/s  Area 2:.02secx60N= 1.2kgxm/s  Area 3:.5x.02secx60N=.6kgxm/s Total Impulse = 2.4kgxm/s

 Elastic: momentum and kinetic energy are conserved  The only true elastic collisions are atomic particles and subatomic particles  We use billiard balls to model elastic collisions because they lose very little KE.  Inelastic: momentum is conserved but KE is lost due to deformations, sound, etc.  Most collisions fall into this category  If I lose ANY KE (due to friction, sound energy, etc)

 Perfectly Inelastic: momentum is conserved but KE is lost due to deformations, sound, etc, AND the objects stick together after collision!  Example: cars that collide and stick together

 The point about which a body moves as if all forces were exerted there.  The point has an x and y component.  SI unit is the meter (m)

 Center of raft is (6m, 6m)