Physics pp

• Amplitude


  Measure of the size or magnitude of a wave
• Frequency


  Number of waves per second
• Movement of particles


  1. Solids - vibrate around one fixed position

  2. Liquids - move in all directions each other

  3. Gases - move at all different speeds in random directions
• If a sound has a large amplitude


  It tells us the sound is loud
• Photosynthesis does not take place at night because there is not enough light energy
• Nutrients are absorbed in the small intestine
• Contact forces


  • Friction
  • Air resistance
  • Water resistance
  • Tension
  • Upthrust
  • Normal reaction
• Non-contact forces


  • Gravity
  • Magnetism
  • Electrostatic
• Forces on a travelling car

  • Air resistance
  • Friction
  • Weight
  • Thrust
  • Normal reaction
• Forces on a cyclist

  • Normal reaction
  • Weight
  • Thrust
  • Air resistance
  • Friction
• Forces on a floating object

  • Weight
  • Upthrust (only in liquids)
• Forces needed to start an object moving

  • Force
• Things a force can change

  • Speed
  • Direction
  • Shape
• Forces that can act from a distance

  • Gravity
  • Magnetism
  • Electrostatic
• Balanced forces


  Object will remain stationary or travel at a steady/constant speed
• Unbalanced forces


  Object will start/stop moving, speed up/slow down, change direction or change shape
• Objects will float when upthrust and weight are equal, and sink when weight is larger than upthrust
• Calculating upthrust


  Upthrust = Weight in air - Weight in water
• Ways energy can be shifted from one store to another

  • Heating
  • Radiation
  • Electrical working
  • Mechanical working
• Energy is stored in the candle wax
• Energy is stored in hot water as thermal energy
• Energy is stored in a stretched bungee cord as elastic potential energy
• Energy is stored in a cell as chemical energy
• When a wind-up toy is moving, energy is stored as kinetic energy
• Oscilloscope trace A


  Represents the highest pitched sound with the shortest wavelength/most waves visible
• Oscilloscope trace B


  Represents the loudest sound with the largest amplitude
• Ultrasound is a sound with a frequency above 20,000 Hz
• How ultrasound is used for imaging

  Transmitter sends out ultrasound, it travels through and reflects off the object, receiver detects the echo and uses the time taken to build an image
• Infrasound is a sound with a frequency below 20 Hz
• Infrasound is used to monitor earthquakes, chart rocks and find petroleum under the Earth
• Thermal energy is anything that is in the form of heat
• Gravitational potential energy is the energy stored in the object due to its position above the ground
• Elastic potential energy is the energy stored in a stretched string or elastic object
• Kinetic energy is the energy of a moving object, measured in joules (J)
• Chemical energy is energy stored in the bonds of chemical compounds, like atoms and molecules. This energy is released when a chemical reaction takes place. 
• Electrical energy is energy transferred by an electric current through wires.
• Radiant energy is energy carried by electromagnetic waves, including visible light, radio waves, microwaves, X-rays, gamma rays, etc.