2ndweek

• Momentum involves motion- an object must be moving at a certain velocity.
• Momentum involves mass- the more massive you are, the more difficult to change your state immediately.
• 2 factors of momentum: motion and mass
• Newton's Second Law of Inertia- explains what happens to the motion of a body when force is absent on the body.
• Linear momentum- is a measure of the difficulty encountered in bringing an object to rest.
• Impulse- is the force needed to produce a change in the body's momentum through a combination of changes in its mass and/or velocity.
• Impulse-Momentum Theorem- when a body is acted upon by a resultant force the body is accelerated in accordance with Newton's second law of motion.
• Conservation of momentum- when two objects collide, there are short term forces that act on them upon contact.
• Energy- is conserved in the collision, but the type of energy usually changes.
• Perfectly Inelastic Collision- these objects "stick together" after the collision and move as a single unit at the same velocity.
• Perfectly Elastic Collision- the total kinetic energy is the same before the collision as after the collision.
• Elastic- such as two steel balls that separate after collision; all other collisions in which the total kinetic energy after colliding is less than before collision.
• Inelastic- such as clay colliding with other objects, where the colliding bodies stick together and move as one unit after collision.
• Partially Inelastic/Elastic Collision- the objects do not "stick together" after the collision; they move with different spreads. Thus, the collision does not meet the criterion for a perfectly inelastic collision.
• Equations:

  p=mv; kg x m/s

  f= ma

  f= m *change* v/*change* t

  f*change*t= *change* p; where f*change*t is the impulse in Newton-second (N-s), *change* p is the unit in kg x m/s.

  f= ma = m *change* v /*change* t OR f*change* t= m *change* v

  f x t= mvf - mvi

  m1 v1 + m2 v2 = m1 v1' + m2 m2'