SCIENCE 9

• Momentum


  Mass in motion
• Momentum


  • Depends on mass and velocity
  • Defined as the product of mass and velocity (p = mv)
• Investigating Momentum

  1. Place board at 30 degree angle

  2. Label distances on board

  3. Place block at 10 cm

  4. Record time and stopping distance for toy cars at different initial positions
• The heavier object is more difficult to stop because it possesses a greater inertia in motion which depends on an object's mass and velocity
• Newton's First Law of Motion


  Also known as the Law of Inertia
• For objects moving at the same velocity, a more massive object has a greater inertia in motion therefore a greater momentum
• Two identical cars with different velocities

  The faster car (Car A) has more momentum and is more difficult to stop
• Momentum


  • Depends on mass and velocity
  • Defined as the product of mass and velocity (p = mv)
• For stationary objects where the velocity is zero, the momentum is also zero
• Momentum is a vector quantity
• Elastic collision


  When a ball hits the ground and bounces to the same height
• Inelastic collision


  When a ball hits the ground and sticks
• All other collisions are partially elastic
• Impulse


  Force applied over a period of time (J = F*t)
• Impulse


  Equals the change in momentum (J = m*Δv)
• Collision


  The sudden, forceful coming together in direct contact of two bodies
• Elastic collision


  • Bodies collides and move away from each other
• Inelastic collision


  • It occurs when two objects collide and do not bounce away from each other
• Collision


  • If you raise one ball and let it collide with the other four balls, what happens?
• Momentum transfer


  How is momentum transferred?
• Conservation of Momentum


  1. Total Momentum Before Collision = Momentum of ball 1 + Momentum of ball 2

  2. Total Momentum After Collision = Momentum of ball 1 + Momentum of ball 2

  
  

  BEFORE

  m1 v1(before)+m2v2(before) =

  AFTER

  m1v1(after)+m2v2(after)

  
• According to the Principle of Conservation of Momentum, the total momentum before a collision is equal to the total momentum after the collision if no external forces act on the system

  
• Application of Conservation of Momentum

  • What happens when a bowling ball hits the pins? If there is no other forces applied. . . The total momentum of the bowling ball is transferred to the pins and the pins go flying. The momentum that the pins gained is equal to the total momentum of the bowling ball had before it hit the pins. Momentum is not lost or created only transferred.
• Application of Conservation of Momentum


  • Rocket gains momentum in the up direction, the hot gases gain momentum in the down direction
• A 12,000kg. Railroad car A is traveling at 2m/s when it strikes another 12,000kg. railroad car B that is at rest. If the cars lock together, the final speed of the two railroad cars is 1m/s
• Energy


  The capacity or ability of something to do work
• Forms of Energy


  • Electrical Energy
  • Sound Energy
  • Mechanical Energy
  • Heat Energy
  • Light Energy
  • Chemical Energy
  • Nuclear Energy

  
• Electrical Energy


  • A type of kinetic energy caused by moving electric charges. The amount of energy depends on the speed of the charges – the faster they move, the more electrical energy they carry.
• Electrical Energy


  • Battery
  • Cp
  • Lightning
  • Flashlight
  • Vacuum
• Sound Energy


  • Comes from vibrations moving through something. Solids, liquids, and gases all transmit sound as energy waves.
  • the result when a force, either sound or pressure, makes an object or substance vibrate.
• Mechanical Energy


  • The energy that is possessed by an object due to its motion or due to its position.
  • can be either kinetic energy (energy of motion) or potential energy (stored energy of position).

  
• Heat Energy


  • The result of the movement of tiny particles called atoms, molecules or ions in solids, liquids and gases.
  • Heat energy can be transferred from one object to another. The transfer or flow due to the difference in temperature between the two objects is called heat.
• Light Energy


  • A kind of kinetic energy with the ability to make types of light visible to human eyes.
  • Light is defined as a form of electromagnetic radiation emitted by hot objects. Light contains photons which are minute packets of energy.
• Natural Light Source


  • Sun
  • Fireflies
  • Stars
  • Lightning
• Artificial Light Source


  • Light Bulb
  • Fireworks
  • Glow Sticks
  • Candles
• Chemical Energy


  • Energy stored in the bonds of chemical compounds, like atoms and molecules. This energy is released when a chemical reaction takes place. Usually, once chemical energy has been released from a substance, that substance is transformed into a completely new substance.
• Nuclear Energy


  • A form of energy released from the nucleus, the core of atoms, made up of protons and neutrons. This source of energy can be produced in two ways:
  • fission – when nuclei of atoms split into several parts – or
  • fusion – when nuclei fuse together.

  
• Energy transformation is governed by the law of conservation of energy, which states that energy cannot be created nor destroyed, it can only be transformed from one form to another.
• The total energy in an isolated system is constant.
• Most energy transformations are between Potential Energy and Kinetic Energy.