Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.



Published on

AP physics
Momentum and energy

Published in: Education
  • Be the first to comment

  • Be the first to like this


  1. 1. AP Phys B Test Review Momentum and Energy 4/28/2008
  2. 2. Overview  Momentum • Center of Mass • Impulse-Momentum Theorem • Conservation of Momentum  Energy • Work-Energy Theorem • Conservation of Energy • Elastic and Inelastic Collisions
  3. 3. Momentum  Momentum • Momentum is defined as: • The rate of change of momentum of an object is equal to the net force applied to the object.   p m v= Σ ∆ ∆   F p t =
  4. 4. Conservation of Momentum  Conservation of momentum states that: the total momentum of an isolated system of objects remains constant. • Isolated system: no outside forces acting on the system • Tip: Break the momentum of each component up into horizontal and vertical components: these are independent of one another!
  5. 5. Collisions and Impulse  Impulse-momentum theorem defines impulse and says that the impulse on a system will be equal to the change in its momentum.   F t p∆ ∆=
  6. 6. Center of Mass  The center-of-mass of a collection of particles if given by the following equation: • The total linear momentum of a system of particles is equal to the total mass M of the system multiplied by the velocity of the center of mass of the system. • Extended systems use this formulation for Newton’s Laws too. x M m xC M i i= 1 Σ
  7. 7. Work and Energy  Work is merely a force applied on an object over a certain distance.  Kinetic Energy is the energy of motion.  Potential Energy is the ability of an object to start/stop motion. • Gravity: Elastic W F d= c o s θ T m v= 1 2 2 U m g h= U k x= 1 2 2
  8. 8. Work-Energy Theorem  This principle states that the work done on an object is equal to the change in kinetic energy of an object W T= ∆
  9. 9. Conservation of Energy  Conservative vs. Non-conservative Forces • Friction  Conservation of Energy: The total energy of an isolated system cannot change. • Shift between potential and kinetic energy.
  10. 10. Power  Power is defined as energy over a given time period.
  11. 11. Collisions  Elastic Collisions • “Rubber” – things bounce off. • Both energy and momentum are conserved.  Inelastic Collisions • “Gluey” – things stick together • Only momentum is conserved!
  12. 12. Rotational Mechanics  Radians  Angular displacement, velocity, acceleration  Moment of Inertia  Torque  Angular Momentum
  13. 13. Simple Harmonic Motion  Period and Frequency  Oscillatory Motion • Springs, Pendulums • Conservation of Energy • Position as a function of time x t A t( ) c o s ( )= ω