Science 9 4th Quarter 2

• Momentum

  -          It is a property of a moving object that describes its tendency to keep moving along its current path.

  -          It is a mass in motion.
• v  Anything at rest doesn’t have a momentum even if it has mass.
• -          It is the product of mass and velocity.

  Ø  p=mv

  Ø  (mass is always in kg & velocity is m/s)
• ·         Momentum depends on mass and velocity.

  v  An object’s momentum will change if its mass and/or velocity (speed and direction changes, while mass is constant).
• Impulse

  -          Change in momentum of an object when force is applied over a period of time.

  -          Product of force and time that acts on an object.

  -          SI unit of Impulse is N.s (Newton – unit of force which is expanded to kg m2/s2)

  -          The formula is I = Ft
• Impulse-Momentum Theorem

  -          The change of momentum of a system is equal to the impulse of the force it experiences..

  -          Ft = mv – mvo
• Energy

  -          It is the ability/capacity to do work.

  -          It can exert force on another object to do work on it.
• Mechanical Energy

  -          Energy possessed by an object due to its motion or due to its position.

  -          It can be either kinetic energy (energy of motion) or potential energy (stored energy of position).

  -          It is the sum of Potential Energy and Kinetic Energy.

  Ø  ME = PE + KE
• Potential Energy – object due to its position. It has something to do with Gravitational Potential Energy.

  Ø  PE = mgh (All these factors are directly proportional.)
• Elastic Potential Energy – the energy due to the configuration of springs of rubber bands.

  Ø  PE = ½ kx2
• Kinetic Energy – the energy of a body because of its motion.

  Ø  KE = ½ mv2
• The Law of Conservation of Momentum

  -          In an isolated system the total momentum of the two objects is before its collision.

  Ø  (m1v1 + m2v2) initial = (m1v1 + m2v2) final
• Types of Collision

  1.          Elastic Collision – it collides elastically and bounces off without any loss of kinetic energy.

  Ø  (m1v1 + m2v2)

  2.         Inelastic Collision – it may stick together momentarily but may rebound (it bounces off sometimes) and the kinetic energy will reduce.

  3.         Perfectly Inelastic Collision – it is a type of inelastic collision where an object sticks together after colliding and move as one unit. (But there may possibly have a deformation).

  Ø  (m1v1 + m2v2) initial = (m1v1 + m2) v2 final