Physics

• Linear momentum


  The product of the mass and velocity of the object.
• Linear momentum


  Vector

  Is the same direction as the velocity vector.
• Calculate linear momentum (one direction)


  p = mv
• Newton's second law in terms of momentum


  The net force acting on an object is equal to the rate of change momentum.
• Constant mass


  Fnet = change in p/change in t
• Isolated System


  Has no net external force acting on it
• The law of conservation of linear momentum


  The total linear momentum of an isolated system remains constant (is conserved).
• Elastic collision


  A collision in which both momentum and kinetic energy are conserved.
• Inelastic collision


  A collision in which only momentum is conserved.
• Define impulse


  The product of the net force and the contact time.
• Impulse


  J/p = Fnet x change in time
• Impulse


  Vector

  In the same direction as the net force vector

  Impulse and change in momentum is equivalent:

  J = change in p
• Define Work done on an object by force

  The product of the displacement and the component of the force parallel to the displacement.
• Wnet


  W = F x displacement

  W = Fnet x displacement cos
• Define gravitational potential energy


  The energy an object possesses due to its position relative to a reference point.
• Work


  Scalar

  Measured in J

  If energy is gained - work done +

  If energy is lost - work done -
• Gravitational potential energy


  Ep = mgh
• Define kinetic energy


  The energy an object has as a result of the object's motion.
• Kinetic energy


  Ek = 1/2mv^2
• Mechanical energy


  The sum of gravitational potential and kinetic energy at a point.
• Mechanical energy


  Em = Ep + Ek
• The law of conservation of energy


  The total energy in a system cannot be created nor destroyed, only transformed from one form to another.
• The principle of conservation of mechanical energy


  In the absence of air resistance or any external forces, the mechanical energy of an object is constant.
• Work-energy theorem


  The work done by a net force on an object is equal to the change in the kinetic energy of the object.
• Define power


  The rate at which work is done / the rate at which energy is transferred.
• Power 


  Unit: watt (W)

  1 W = 1 J.s^-1
• Power 


  P = W/t
• Constant velocity


  If a force causing an object to move at a constant velocity, calculate the power using P = Fv
• Define Efficiency


  The ratio of output power to input power
• Percentage efficiency


  % efficiency = powerout/ powerin x 100